BorlandC proj

HI,
i'm a beginner in C prog & I've got a final proj in BorlandC in which I'm supposed to design excel spreadsheet! :(
the program is supposed to read data from a file, if the user wants, it should show the contents of a cell, change the content of a cell, delete a cell, or add new data thats gonna be stored in the same original file!
so as user inputs, it should understand : save 'filename', load 'filename', set cell= formula, show cell1:cell2...

I'm so confused about it and I don even know how to start! :( if there's anyone here willing to give me a hand on this, I would really really appreciate it!
if u know somethin, plz explain it using borlandC code and preferably go by an example too to make me get it better!

thanx ahead
all the best
Mary

Is this going to be a console program, or a GUI program?

If it's a GUI program, are you expected to write it all yourself, or are you allowed to use various pre-defined controls?

What kind of data can be stored in a cell, like "text" and "numbers".

For numbers, what kinds of expressions are supported, say +-*/ ?

Are expressions allowed to refer to other cells.

Break the problem down into a series of manageable steps, each of which adds a new feature based on what was there before. But plan out what all those steps will be so you don't program yourself into a corner.

There *might* be a few of us who still have Borland C. <cough, cough>

Your description of the project's requirements is incomplete, though. Get those required details and bring them front and center NOW, before you start thinking about your design for this program.

Salem's given you loads of good advice. All I'd add is don't wait, start asap, and don't despair. There are some pretty logical work to work through these things, but if you have no idea of how to start, it will take a LOT of work and time. More than you would expect.

When you get the above, post them up, and post up your POA (Plan of Attack), for solving this problem. I'm a little unsettled by your self-description as a beginner, and you having to do a final project.

Hi!
thanks alot for ur replies and ur advices!
sorry for the incomplete discription! it was jus becuz I wasn't sure if there is actually anyone to help me!
Um.. first of all its a console program, so no graphical stuffs goin on!
whatever the user wants to see, he'd simply see it in the console window after running the program! like any other simple prog!
The cells contain numbers only! I mean each operand for a cell could be only a num or another cell having a num, like B23.
and the kind of math expressions supported are: +, -, *, /, sin/cos/tan/cot/ sum/ average, and a combination of all these.
so first of all I'm supposed to have a calculator program which given a string of math expression, would get the result! this calc has to work using 2 stacks, operators and operands! and it has to watch out for the paranthesis too if there are any on the math expression! i guess it should work kind of like a reverse polish notation calculators!
yeah the expressions are allowed to refer to othr cells too! like:
A1 = 2 - 3* avg(B23:D46)
or
A1 = 2 - 3* B23

and one other thing, like a real excel prg, in this prg the rows of the table are named using numbers and the columns using alphabets(A, B,..). so if the num of columns got more than 26, the 27th col would be AA, the 28th AB and so on.
I know, this proj needs lots of time considering the fact that I'm no Pro in that!!! and thats why I'm so stressed out! :( but I'm hoping that u guys can help me a bit go thru it successfully!

thanks ahead
regards...

You will need to write functions for the following:
1. Placement and formatting of data on screen, so that you can see different columns and rows, in different formatting [e.g. number of decimal places and such].

2. Variable handling - retrieving the content of a variable. You probably want to "track" the type of the content - in C++ I would use inheritance to make a basic variable class and inherit from that for formula, string and number content.

3. Calculation. Note also that you probably need to do "recursive formula detection", e.g. A1 = B1 * 3; B1 = A1 + 4 can't be solved, because for A1 depends on B1 which in turn depends on A1, so you can never solve it. And yes, you will (probably) need to use a "stack" in your calculation. And recognize your functions (average, sin, etc).

4. Some file functions to save/open a calculation sheet.

None of this is TERRIBLY complicated, but as you say, it will take some time, and you will certainly learn a fair bit. Not a bad project, and I would find it quite interesting to solve [although I would probably use C++ for it - both because it offers some help to solve some of the problems, and because it would improve my C++ skills, which is where I feel I need to learn more...]

--
Mats

That's a much better description, but also confirms a larger amount of work that needs to be done, for your project.

Your idea for this, sounds good. A function which can handle a complicated string, changing it into a string for a reverse polish calculator function to deal with.

I don't believe your project will run into trouble with Turbo C on a console window; it's the overall design and logic that will be the big hurdles.

Have you read Wikipedia on RPN, done some Googling on it, and have some code or pseudo-code, for that? Any problems, so far?

Keep in mind that we are helpers, we are not homework DOER's. You show us your work, and tell us what your problem is. I'm sure we can make good suggestions or correct code problems. Some students come here expecting whole programs or several functions to be coded up for them. They are quite disappointed in us, and we are quite disappointed in them. We have this odd belief that a programmer should be able to actually program. :)

If I were to do this (and you may have as much programming experience as I do, since I'm a hobby programmer only), I would lay out the pseudo-code, with each function on a different page (or pages), of notebook/legal type paper. Put off the details for now. Get the flow right, and then pick some easy functions to get working, one at a time, testing as you go.

I think particularly, I would concentrate on the different aspects of the RPN calculator, as soon as the general flow pseudo-code was done. I see that as the heart of this program, and something that will need more testing than the other functions.

Another approach would be to tackle the harder parts as separate programs, so for example you might have

Code:

---

double evalExpr ( const char *expr ) {
  // lots of code, calling many other functions
  return result;
}
int main ( ) {
  printf( "Result=%f\n", evalExpr("1+2/3") );
  printf( "Result=%f\n", evalExpr("sin(0.5)") );
  return 0;
}

---

You can work on that in isolation without worrying about say screen handling, and when it comes time to add it to the main code, all you do is comment out the local main() and call the function you've already written and tested.

Another example would be to think about how to represent the cell data as this is going to be your central data structure. Imagine how that could be passed to a function to display a grid of values, or saved in a file.

I agree with Salem's suggestions, and indeed that is why I put groups of functions that "belong" together.

Also, getting the data structures sorted early on helps avoiding major changes later on.

--
Mats

thank you all for ur replies! u guys r full of gr8 ideas! :o
considering the calculation part only, in Mats' beautifully listed steps, so the idea of using stacks sounds good! yes Adak, I've actually searched a whole lot about RPN and have almost got the heck of it!
yeah I know u guys r here to correct/suggest things and we r the ones putting these suggestions/corrections together to write the whole prgm; but just doin what u guys r supposed to do, makes me more than happy here, cuz thats exactly what i need! :)
As Salem suggests, I'm just focusing on the evalExpr part for now, to not get myself confused!
I've thought of it thoroughly and have written a long piece of code in BorlandC (thats the one I have to have my proj running in). its only the prgm for the calculator and nothing else!
but guess what, it doesn't work at all!!!:( and I can't figure out whats wrong! :(
I've attached it in this msg and would be thankful if u guys have a look and tell me whats wrong!
Note1: its been assumed that there is a space btwn each element of the expression given by the user.
Note2: I have also assumed, that there are no paranthesis in the expr for now cuz that sound a bit complicating for me at this moment!
Note3: So sorry if the code is too long and maybe hard to follow! afterall I'm a beginner!

thanks

I would move ALL of the calculation code [but not the "ask the user for something to calculate" into it's own function - because that's what you need later.

Also, do not EVER use gets() - it's the absolutely worst possible function you can ever use. fgets(str, sizeof(str), stdin) will do the same thing, but it won't overwrite whatever else is behind the string if someone inputs some really long string.

You may want to have a "separator" string, which for example takes parenthesis, rather than using just " ".

You look for "cos" twice.

You probably want to check if the value is a number, rather than blindly calling atoi().

Surely you don't need to check for trig functions over and over again - there should be no need for that.

Your stack push and pop functions should check for overflow/underflow situations.

I'm sure your comp_prec() function can be made simpler [with just two comparisons and an "else", as there are only three options: Equal, lesser or greater, so once you have compares two, the third one must be "it"].

Thanks alot 4 ur reply!
ok yes, later I am goin to put all the calc code into a single function and call it whenever needed, but as I said right now its only the prog for a calculator!

about fgets(...), isn't it only to be used if we are dealing with files?!

and about the space btwn elements, we were told by the prof to assume it this way to make it simpler! but what u mean exactly by a separator string??

about checking if the value is a num, well I checked for the case of operators, then trig fncts, so otherwise it'd be a num; but yeah u're right cuz there might be an error made by the user, he might have entered a letter instead of a digit! so how do I check for that? any special C library funct that could be used?

anyways, thanks alot for ur good points, but still, why does the prgm not work at all?? the mentioned errors diddn't have much to do with the logic and the process I followed to calc the result, so whats wrong that, while even having a flawless expression as input, it won't work??:(

splitting your "calculator" into a function may actually help you in other ways too - for example you can solve something like 1 + (2 * 3) by calling the calculator again with "2 * 3" from the inside of the parenthesis - although this may not be the only way to solve this type of problem. But more imporantly, if you split it into a function, you can then use that function DIRECTLY from the actual spreadsheet program, rather than THEN having to copy it out and figure out what parameters to pass, etc, etc.

fgets is definitely useful and meaningful to use on stdin - stdin _is_ a file - just so happens that the file is the standard input which is usually not a "file" in the context of "something that resides on a disk somewhere", but it's a file in the operating systems perspective.

Yes, someone may enter something you don't expect [maliciously or by mistake].

As to why it doesn't work, I haven't even tried to compile it.

If you are going to succeed in writing a larger application, then you will have to learn how to debug your code, so I would suggest that you do that. I'm not saying this to be nasty, but rather because I know how to debug things, but I can't do your work for you, so you need to start understanding how to find out why your code doesn't work. A starting point would be to try to figure out WHAT actually works.

If you have SPECIFIC questions, please feel free to ask - but asking "why does my 230 lines of code not work" is not a particularly specific question.

--
Mats

ok I got it! thanx for the explainations!
yeah you're absolutely right and I'm sorry for asking u such a thing! but I know how to debug my programs, as this is not the first C proj I'm having(well this is the first hardest though) and have learned alot as u said! and I have actually debuged this one several times too but I can't see where I've gone wrong! I'm gonna try my best still, though! but trying to be specific, do u see anything wrong with my operators' push/pop functions and the way I've called them inside main fnct??

thanks ahead

I actually spent a few minutes compiling and adding debug code to your push/pop functions, and it appears [from my brief check] that you are calling pop more times than you call push.

Code:

---

plz enter ur expression:
1 + 2
Token=1
calc.c: 109: Push 1 to -1
Token=+
calc.c:132: popop 0 from -1
calc.c:133: pop 2089879346 from -2
calc.c:134: pop -1 from -3
calc.c: 136: Push -2147483648 to -3
calc.c: 137: Pushop 43 to -2
calc.c: 184: Push 0 to 738197503

---

Line numbers may not match exactly, as I added a few lines.

You also should use "int main()" rather than "void main()" and add "return 0" at the end of your main function.

Gcc that I use, also complained about your line 78, where you are declaring a int i inside the for-loop, which is not valid standard C89.

--
Mats

Hey!
I finally figured out the calculator program! :) I actually forgot about what I had, and did it over again, a bit differently though, and now it seems to be running properly for most of the expressions I have tested!
Now do u have any suggestions as to what would be the next thing I better do now that I've got the calc part o.k.?!
I'm also a bit confused about the table! I am supposed to use malloc for allocating a 2D array and I know how to do that perfectly, but then how do I make the columns naming alphabetically, the way I'd explained it before !? and inside my calc prg I also need to have the case where the operand is the content of another cell of the table, say B23! so it has to get that content and replace its value in the expression! I'm a bit confused about how to do that part too! sorry if I don sound very specific again!
thanks in advance...

Don't stop de-bugging the calculator part! That's the heart of the whole program. Finish it, and THEN let's see what else might be next to do.

You might keep the column headers in an array of strings. No particular need to use them internally in your program that I can see.

Hi,
yes I know thats the core of the whole prgm but I've checked it out for many cases and it still seems to be working!
jus one more thing about the calc part, as Mats had pointed out before, its not a good thing to have no condition-checking for the case of operands and blindly saying that if the input is none of ops so its an operand(thats what I've done). I was thinking of figuring out a condition for the case of operands but I didn't get anywhere! :( I was gonna use the ascii codes but that wasn't a good idea; then I thought of the lib func isDigit but that will only work for 1dig numbers! do u have any suggestions?
and also I am trying to write a function that given the characteristic of a cell as an operand, like AB57, it will return the num of rows and cols, so using these two, we can trace that cell in our 2D array and get the content and replace it in the expression instead of AB57! so like for AB57 it will return row 57 and column 28 I guess! do have any suggestions as to how to write such a function?(its getting AB57 as an string)

So for your variable store, you need two things:
1. A management function to allocate/track what cells you have.
2. A function that takes a reference to a cell and returns the contents.

You probably will need some more functions as helpers, so I would start a new C file called "cells.c" or some such, just to keep the code nice and tidy. If you don't split it early on, it's likely to lead to more work when you DO find that you HAVE to split it later on. Unless you go completely silly, it's better to have many small files than to have a few large ones. Obviously, the splits should be done at some logical levels, such as one file that handles expressions/calculations, another that handles cells, and so on.

--
Mats

I would use an array of structs for this project. The "str" portion of that cells struct, would have the string ID or name, for that cell.

If you don't group your data together, for each cell of the array, it could be a real logical nightmare, imo.

I would use the ascii codes to determine what input is and is not, a valid number for input. If a char is >= ascii value of '0' && <= ascii value of '9', then doesn't it have to be a number?

Quote:

---

Originally Posted by Adak

I would use an array of structs for this project. The "str" portion of that cells struct, would have the string ID or name, for that cell.

If you don't group your data together, for each cell of the array, it could be a real logical nightmare, imo.

---

I completely agree - the content of a cell should [probably] be stored as a struct.

Quote:

---

I would use the ascii codes to determine what input is and is not, a valid number for input. If a char is >= ascii value of '0' && <= ascii value of '9', then doesn't it have to be a number?

---

If we assume that the "number" is an integer, then yes.. Floating point (which I think eventually will have to be introduced in this project) could also start with "." (as in .1 or .0001). Numbers can also start with '-' for negative numbers.

--
Mats

instead of using acsii codes you can call a function isdigit for the same purpose

ok yeah, I am goin to use a struct for each cell! but still the stringID part of it needs to be defined, using the function I talked about before!
as Mats said "A management function to allocate/track what cells it is" is what I need too! and I need some suggestions for how to write such func that looking at the string ID like AB57 would return 57 and 28 as num of rows and cols to track that cell?

and about the suggestions for checking a num, well first of all as Mats said, my oprnds are of type float!
and also both the case Adak suggested, (char is >= ascii value of '0' && <= ascii value of '9'), as well as the idea of Vart,both of which I had thought of before, wouldn't these only work if the num is a single digit one? I mean what if we have entered 12, 57, 109,..as operand? then how to use ascii codes or isDigit lib func for these cases?

The string ID can be another member of the cell's struct. Isn't that easiest and most logical?

I believe every char in your input is going to have to be checked, one by one, anyway. 127 is going to have it's 1 checked, then the 2, and finally the 7. So why not use isdigit for that?

You'll have enough to keep you busy with other needed code, don't worry! :)

Yes, of course you should go with floats or doubles, where needed.

So what part of "translating An (where A is one or more a letters 'A'..'Z' and n is one or more digits 0..9)" into a number are you having problems with? By the way, it may be better to translate it to a "Y, X" coordinate pair, rather than one integer value [you can combine them later].

There is a function called "isdigit" in type.h, which will tell you if a char is a digit or not - that is '0'..'9'. To check that something is a valid floating point number is more complex, as they can contain other things - easiest is probably to extract the operand as a string, then use strtod() to convert the string, and check both the return value and the "where we stopped" pointer, to see if ALL of the string got accepted by strtod() - I would recommend writing a tiny program that takes a user-input string and runs it through your conversion routine, so that you can check that on it's own - it's important to get it right!


--
Mats

ok Adak, so u mean instead of tracking the cell using the row & col num, we simply compare the ID we have with the ID of each cell and see which one matches???
yes, I know there's alot more to do and I'm not left with that much time! :(
and about isDigit, ok I think I got it, I have to try what Mats suggested though! but thanx for ur replies!
So whats ur suggestions for the next thing I have to do now that the calc part is done?

Seeing as you still HAVE to convert the number, I think my suggestion is "better", since the "strtod" (or strtol for integers) do all the checking you will ever want, instead of "you" doing some checking and then passing it to strtod() to do more checking.

And just to make sure, it's NOT "isDigit", but "isdigit".

I suggest you start working on the cell-structure, storing and retrieving cell contents to start with, and then integrating your calculator to use the retrieval functions to reference cells.

--
Mats

oh and for Adak's idea, how is each cell assigned an ID like AB45 ? and also how do we convert the alhpabetical col into its value so like AB to 28?!

Quote:

---

Originally Posted by mary18

oh and for Adak's idea, how is each cell assigned an ID like AB45 ? and also how do we convert the alhpabetical col into its value so like AB to 28?!

---

In Adak's suggestion, I suppose you just store cells in a [large] array, and just read through the list until you either find one that matches or the end of the array. I'm not sure how well that would work tho', as you probably still need to track how large your 2 dimensions are of your "active data".

But it's actually not very hard to translate the values from string to "two numbers". Think about it:
A = 0,
B = 1,
...
Z = 26
AA = 27
AB = 28
...
AZ = 51
BA = 52
BB = 53
...

Do you see something you can use in that?

--
Mats

Mats, unfortunately I can't see anything! :( like A to Z is 0 to 26, and then the next 26 would be AA to AZ and so on! but I can't figure out a loop for that! like we can't go by comparing what we have with each letter, like if its A then its 0 if B then its 1... uh.. I know it sounds so simple as it should be but I can't figure it out! :(

So how do you convert a number (e.g "12") into an integer value of 12?

--
Mats

what do u mean? 12 is already an integer number! what coversion r u talkin about!? like int number =12;

I'd not use the stringID member for each cell struct, Mary. It seems straight-forward to just use the letters for numbers, like Mats suggested.

Sorry if I confused you, but I was a bit confused myself. I didn't think we'd need a string ID at first, but you convinced me, we would. :)

I'm such a push-over sometimes. :) :)

Hey Adak!
thats ok! :) ;)
At least thats the only part u might have got confused about! I'm confused about the whole thing following the calc part! :(

Quote:

---

Originally Posted by mary18

Mats, unfortunately I can't see anything! :( like A to Z is 0 to 26, and then the next 26 would be AA to AZ and so on! but I can't figure out a loop for that! like we can't go by comparing what we have with each letter, like if its A then its 0 if B then its 1... uh.. I know it sounds so simple as it should be but I can't figure it out! :(

---

Actually, A to Z would be 1 - 26 (or 0 to 25! but I'd skip the 0 element here, and start with A = 1, Z = 26, as we all learned in school.

Mary if you you have a string like:
AA = 27
Since AA has two letters, it's > 26. Second A tell you it's one greater than 26.

The first A is in the "26's" column, see?

AB = 28
We have A 26's, so 1 * 26, plus B one's, so 26 + 2 = 27
...
AZ = 52

BA = 53
Since BA has two letters, it's > 26. How much greater? Well, we have "B" 26's, so 2 * 26, for the B, and then 1 more for the A.

It's just like base 10:

10's column,| 1's column

except it's base 26:

26's column,| 1's column

That's what you meant, right Mats? (I'm sure it is!)

ok, I see the point now!
how about this? like the ascii code for A through Z is 65 through 90 right?
so if we have a single letter like A thru Z, then we'd do: ascii code of that letter minus 65. so if its A, then 65-65=0,..., if Z, 90-65 is 25! and the difference gets returned!
then if its a two letter one like AA thru ZZ, we'd get the ascii code of the first letter minus 65 plus 26. so if its AA it'd be asciiCodeOfA= 65-65+26=26
if its ZZ => 90-65+26=51
do u think this'll work too?

That's what I meant. And you can actually use A=1 all the way through.
Just remember that C arrays start at zero, so A1 is actually cell [0][0], and C9 is [2][8] for example. So you need to (at the point where you access the array, at least) subtract one from each of the Y and X indices of the array.

--
Mats

Lots of times I do that (subtract the indicies), but in this case, I would not advise it.

Just too easy to let the zero'th element, go unused. No more problem! Everything matches up with
what you're seeing on-screen, with the row numbers, and what you learned in elementary with the alphabet.

Guess I'm old-fashioned too, sometimes.

Actually, as long as you don't have HUGE amounts of columns and rows, it makes little difference indeed, and it does clearly make the code more simple.

Mary: Forget my idea of subtracting one. Just use A1 as [1][1] and C9 as [3][9] - it's far easier.

--
Mats

ok now how do we split the letter from the number part, in like AB34?? there should be some str.. predefined funct for that! I was gonna use strtok, but as the sec arg it needs a delimiter and I can not find a delimiter in AB34!
there's also strcspn working this way:
char str[] = "AB45";
char keys[] = "1234567890";
int i;
i = strcspn (str,keys);

and it'll return 3 as the location of the first dig in str[] thats contained in keys too! but thats of no help either cuz it can't split the two!
any other func u guys know of?

Quote:

---

Originally Posted by mary18

ok now how do we split the letter from the number part, in like AB34?? there should be some str.. predefined funct for that! I was gonna use strtok, but as the sec arg it needs a delimiter and I can not find a delimiter in AB34!
there's also strcspn working this way:
char str[] = "AB45";
char keys[] = "1234567890";
int i;
i = strcspn (str,keys);

and it'll return 3 as the location of the first dig in str[] thats contained in keys too! but thats of no help either cuz it can't split the two!
any other func u guys know of?

---

First, I would like to backtrack just a bit on the A = 1, Z= 26 thing. We need A = 0, so we have a placeholder number in our base 26 system. So NEW and improved: (and damninumm that Mats :D ):

A = 0, Z = 25. I still wouldn't use row 0, however.

Now onward and upward.

In hexadecimal (base 16), the numbers are: 0 - 9, then A,B,C,D,E,F. IOW's the letters in hex ARE numbers. In base 26, which you'll use, ALL the letters are numbers, and indicate columns of the spreadsheet. The rows of the spreadsheet, are still in base 10.

I don't know a pre-defined function for separating them. We'll have to roll our own, I believe.
Something like:

Code:

---


int column number
char column string[6] /* holds five letter places we'll use 1-5 */

/* Get the column string */
while(char is not a digit)  {
  column string num++
}
/* Change it to a base 10 number */

for(i = column string num, column flag = 1; i > 0; column flag++, i--)  {
  if(column flag == 1)  /* in the 1's column
      column number += column string[i] - 'A' /* A now is 0 */
 
  if(column flag == 2)  /* 26's column now */
      column number += (column string[i] - 'A') * 26 /* A is now 26 */
 
  if(column flag ==3)  /* 676's column now */
      column number += (column string[i] - 'A') * 676 /* A now represents 676 */

  /* expand as needed, but next column is 17576! */


}

---

The above is off the cuff, and completely untested. Just to show the idea, without using pseudo code.

Another way to do the change to base 10 loop, is to reverse the columns letters before finding their base 10 value. I didn't use that here, however.

O.K. Adak, I see the point! thanks alot for ur reply! :)
by the way seems like u're kinda interested in the A to Z thing! huh?! ;)

I see that A-Z thing as a significant hurdle for your program. I've used base 16 before for a matrix, but not base 26. Had to kick out some cobwebs. :)

Now that we see that A=0 is needed, the code for things like:

Code:

---

for(i = whatever; i < something; i++)
  more code here;

will need to be adjusted in some cases to:
for(i = whatever - 1; i < something; i++)

---

Stuff like that.

yeah I know, this A to Z part has one of the key roles of my prog!
but I think I finally got it working properly! :)
Now do u guys know how to free a memory allocation done for a 2D array?!
like for malloc'ing a 2D array of ints, size m x n we'd do this:

int** 2DArray = (int**) malloc (m * sizeof(int*));
for (int i = 0; i < m ; i++ )
2DArray[i] = (int*) malloc (n * sizeof (int));

so for freeing it, do we have to do somethin like this:

for (int i = 0; i < m ; i++ )
free(2Darray[i]);

does that look all right?!?

Quote:

---

Originally Posted by mary18

yeah I know, this A to Z part has one of the key roles of my prog!
but I think I finally got it working properly! :)
Now do u guys know how to free a memory allocation done for a 2D array?!
like for malloc'ing a 2D array of ints, size m x n we'd do this:

int** 2DArray = (int**) malloc (m * sizeof(int*));
for (int i = 0; i < m ; i++ )
2DArray[i] = (int*) malloc (n * sizeof (int));

so for freeing it, do we have to do somethin like this:

for (int i = 0; i < m ; i++ )
free(2Darray[i]);

does that look all right?!?

---

You also need to free the actual 2D array itself.

--
Mats

> does that look all right?!?
You also need
free( 2Darray );

I assume this is pseudo-code, since 2Darray isn't a valid identifier.

Also, drop the cast on the return result of malloc. The FAQ explains why such a thing is unnecessary.

Yes, that is a peeudo code!
ok so just to make sure, this is exactly what I have to have:

for (int i = 0; i < m ; i++ )
free(2Darray[i]);
free(2Darray);

right?!?

Yes, that looks right.

--
Mats

In Borland C you may need to keep the cast, though. In my early version, I do have to keep it, but your version is much later, so maybe different.

Guys I've got a weird problem in my prog!!! its so crazy cuz I can't get to know whats wrong!:(
I was trying to debug a part of my prg, so stepping over the prg, the way it usually is! everytime there's a printf for getting a string from console, followed by a gets(...) or fgets(...), the way it was all the time is that while debugging, when it reaches to fgets or gets, it'll open up the console window asking the user to enter the string and then once gotten, it'll go back to debugging and stepping over to the next parts!
but now, when I'm debugging this part, it reaches the gets, (or fgets, I tried both) but doesn't come up with console to ask the user for the string!!!
like for example I wanna have A23= 6 + 7 read, and put into the array called statement! (I can't use scanf cuz it'll terminate once reaching whitespace and I can't remove spaces either cuz my prg needs spaces for the calc part to work) so I have the following:

Code:

---

char statement[10]= {0};
printf("plz enter ur expr:\n ");
gets(statement);

---

it goes thru all three lines and the rest but never tries to get the expr once reaching gets! it jus keeps goin blindly! :(

Can you PLEASE use the fgets(...) instead of gets().

So, you probably have used "scanf()" somewhere before the fgets() - it means that you have a dangling newline in the input buffer, and the string is "empty" in gets().

--
Mats

Have you used scanf() AT ALL at any point earlier in the code?

Also, see the FAQ on why using gets() is bad.
An expression of only 9 characters is woefully inadequate.

well I tried it with fgets too; yeah I know gets is the worst choice! I'll try to avoid it!
yes, I do have an scanf before that! cuz its a switch case part, so I have an scanf for reading the case # first!
ok, so what should I do to solve the problem?! anything to put right after the scanf to remove the \n from the buffer!?

Code:

---

while((c = getchar()) != '\n');

---

um... and where do I need to put that? how come u've put a semicolon at the end? is it a typo?!
could u plz extend ur code snippet a little bit so that I can see how this works exactly!?

Quote:

---

Originally Posted by mary18

um... and where do I need to put that? how come u've put a semicolon at the end? is it a typo?!
could u plz extend ur code snippet a little bit so that I can see how this works exactly!?

---

It's just a one line while() line of code. Every statement in C must end with a semi-colon.
It just keeps looping back to get another char from the input buffer, until it reaches the newline char left over from scanf().

It should go just after a scanf() call, to remove the '\n' (newline), from the input buffer. If the input buffer has no newline to get, then you'll need to press Enter before the program will continue. Since there would be no display, it would look like your program had frozen up. :(

You could also just use: c = getch(); as long as you're sure there is just one newline in the buffer.

ok, while I was waiting for ur reply I tried another way of solving it too and it worked! I just put gets("\n") right after the scanf so to bring the newline out of buffer!
Adak I'm having yet another crazy bug! :( remember my Q about freeing a 2D mem allocation?! it doesn't accept it! like there's no compilation or linking error caught, but when I'm debuging, when it gets to the end, the freeing part, it gives an error msg(the error is not part of borlnadC its comin out of my own OS): "CPU has encountered an illegal instruction! close prg to terminate!"
u know btwn my options for user the last one's option #8 to exit the program! and since before exiting its gonna go thru the freeing part, once 8 is entered as the option to exit, the prog freezes! :(

The pseudo code at the top of this page looks right, but you always have to check if the i and m variables are OK.

I'll take a look at it, but you'll need to post up the memory declaration part, and the memory freeing part of the code.

It's always a good check to print up the contents of your malloc'd array, just before you free it, if you're having trouble with the free part. Just to make sure that your array is what you think it is, at that point.

"CPU has encountered an illegal operation" is almost certainly because you are doing one of the following:
1. Freeing memory that you didn't allocate.
2. Overwriting the end of your allocation.

First check is to see if you have the same pointer from the malloc as you do when you free. So step through the malloc code and check out [write the values down] what the pointers are [for small values], and then step through the free-code and check that the values are the exact same ones.

--
Mats

right on target Mats! "1. Freeing memory that you didn't allocate" was the case for me!
I had put the freeing part out of my switch case with no check on the fact that if there's any mem allocated, it needs to be freed, otherwise nothing to free! so then I was trying to exit using case#8 so it'll get out of the switch but still go thru the freeing part while the case of creating a table and allocating mem for it hadn't been chosen at all!! knowing that, I fixed it and it works now!
thanx alot guys!
Also I was trying to hav the case of showing the content of the table whenever the user wants! and I had set a loop in which, I'd printed a dash for any cell thats empty and otherwise the actual contents!
it looks not-too-bad when the size of the table is small! but when it gets bigger the lines get mixed up since the console window can't fit the whole thing on the page and so throws the ones at the end of the rows into the next line! what can I do about it?!

Your cells should be sized so you can fit only X number of them on your screen at a time, along with a small one or two character wide, border on each side. Each cell should be the same size in a column (the widest) probably.

Personally, I see no need to put a --- in each blank cell. A blank cell should stay blank, imo.

Of course, you can't show all the cells of a large spreadsheet on a single page. You have to put a page turner (perhaps centered near the bottom of the page), and when you press an arrow key <- it goes to the left one page, and -> it goes one page to the right. Naturally, if it's already on page one, the left arrow on the page changer, should be greyed out or removed.

Lots of details for a good display.

ok seems like I have to forget about the part related to display,as its gonna take lots of time apparently!
Guys I also have another problem! in this prg the user has 2 options, either to create a table and put in the data to play with too by himself, or he can just load the data from an input file(the first line of which contains the row & col of the table) so using the first line the table is created and data put in!
for the sec option(load) I'm having problems with how to set up the input file to fill out the table in its special manner! (jus so u know my tables' first row and col related to zero indecies is unused and that might cuz problems in loading I guess). and if the file format does not matter so then how should I load from a file in a way to put in the data in a tablular form for filling in the cells of the table!?

Quote:

---

Originally Posted by mary18

ok seems like I have to forget about the part related to display,as its gonna take lots of time apparently!
Guys I also have another problem! in this prg the user has 2 options, either to create a table and put in the data to play with too by himself, or he can just load the data from an input file(the first line of which contains the row & col of the table) so using the first line the table is created and data put in!
for the sec option(load) I'm having problems with how to set up the input file to fill out the table in its special manner! (jus so u know my tables' first row and col related to zero indecies is unused and that might cuz problems in loading I guess). and if the file format does not matter so then how should I load from a file in a way to put in the data in a tablular form for filling in the cells of the table!?

---

Any format you find clear and simple to use is fine, maybe:

A20 44.36
So cell number, followed by a single space, followed by the value to put into the cell.

A is the column, 20 is the row, value is 44.36

After reading the data in from the file, it's just: Array[row][col] = value;

Remember to keep the row as the first dimension of your array, even though the row is the second part of the data from the file.

The data doesn't need to be in a "tabular form", it just needs to be in the right element of the array that corresponds to the cell number. Your display puts the array in the right form. The array is just a plain old 2D array, albeit with base 26. :D

Hi,
I got it but in a different way!
I have the file in such a way that the data for each row is put in a single line in the file and each value on that line is put inside braces! so each time I do fgets for getting each line in the file and then the data are put in the table(only data, no braces)! it worked. now guess what, this phase of my proj is over too! I got it working! :)
now the last phase, is to make our excel functions dynamic. u know in the prev phase, for setting a value to a cell by assigning a math expression to it, it would only get the formula, calc the result and store it in that cell, so what the expression was, is completely forgotten unless the user rentered it!and there's no sign of it in the output file(used to save the table). but now we want it to save the from of the expressions as well so like if we had A1= 3 + 4 * B45 and B45 was 4, we'd see the value of 19 for A1, but if B45 was changed to 0, we wanna see 3 for A1 now! in the prev phase , A1 wouldn't changed with a change in B45.
now we're told as a suggestion to let each cell have the list of all other cells to which its related. so in the struct we had for each cell, we're told to add the list of all cells to which that cell is sensitive so if the cell's content changes, all the cells to which it was sensitive, have to be calculated again!and that recalculation, is done using the formula saved before! for the list, since we don't know how long it is we're told to implement it using linked list!
now I'm a bit confused about how to save the formulas set to a cell! cuz the way my save part worked was jus to get the content of each cell and store it in a file! now since the formula is not put in a cell of table and only the cells to which its sensitive are included in the cell struct, how do I get the formula to save in the file!
this thing sounds somehow unclear to me! I can't get how it works!

I think the best way is to save the formula within the cell, but ignore the "relations to other cells" - instead, when you load the file, rebuild the linked lists of relations at that point. Just treat all cells as if they had just been typed in, if you see what I mean.

I think this is the question you are asking - if you actually are asking about something else, please feel free to ask chastise me and clarify what you want to know.

--
Mats

thanx 4 replying!
ok right, sounds like a good idea to have the formula as a part of the cell struct!
and then when loading the file and building the lniked list, the list is also set to be a part of struct as well, right?! so like in addition to what we had in cell struct, we need two more: the formula and the list!?
u know what I confused about now is that, before in my prg, I had put several cases for user to choose from , like load from file or create a table , set a cell.... so in the case of "load from file" in my input file there were only digits and so after loading the table with values in the file, I'd use other options for setting a cell, deleting ... playing with the values and cells and then saving the new table of value in my output file!
but now would the orignal input file still contain digits only and then later when we load it and play with it, we'd assign formulas to some cells and then that formula is gonna be saved in the output file instead of the value that was assigned to it previously!?
so I mean the original input file is the same, but the output file would be completely different from what we had in the prev phase, right?!?

Yes, you do need several things in the cell structure - however, in the external file (that you load from), you only need a single string. This string is then converted according to the same rules as when you enter a new cell directly. This in turn means that you have to "know" how to distinguish a formula from a number or a string [assuming you support strings, and Excel also supports for example dates as content in cells]. How does this work right now?

Note: If you are storing strings, it may make sense to put them in quotes or some other separator - and you may need to further "hide" any quotes within the string, e.g. if you store strings with double quotes, "Like this", then you will have to make sure that double quotes are "escaped" in the string, e.g:
A string with "string in it"
would become:
"A string with \"string in it\""

You don't have to use backslash, but it's pretty commonly used for this purpose - and you obviously also need to quote backslashes too.

[Or just deny the user the quote character - if you use something rather unusual, like ~ or ^ as a quote, it's unlikely that anyone will worry about it]

--
Mats

Hi,
I'm still stock on the last phase! :(
Mats, I am supposed to do it jus the way I explained it to u! each cell havin the list of all cells to which it is related!
I have a snippet of my prog for which I'm getting an error and can't seem to know why! (I'm having problems using linked list)
u know I had a struct for each cell that now looks like this:

Code:

---

struct cell{
  float content;
  int isValid;
  char *formula;
  relative *list;
};

---

the last variable is the list of relative cells and its of this type(its a node of the list):

Code:

---

struct relative{
  relative *next;
  Address adrs; 
};

---

and again the last variable of this one is of this type:

Code:

---

struct Address{
  int row
  int col;
};

---

so when I get a formula for say A1(first of all I track to see where A1 is, so I get row=1 and col=1 for A1), like A1= 2* B3 +1 - B4...etc, I'm going thru everything after equal sign and then whenever I see a cell address like B3 in here, I follow the same process of getting the row and col num of B3 and store them in two variables like in here crow4=3, and ccol4=2 for B3.
and then I want this info to be part of a new node of the list of relatives, so I do this:

Code:

---

table[row][col].list= (relative*)malloc(sizeof(relative));

---

to create a new node of type relative for that specific cell being A1 here in order to store info about its first relative, B3. then:

Code:

---

table[row][col].list.adrs.row= crow4;
table[row][col].list.adrs.col= ccol4;

---

but I'm getting an error when compiling: "Structure required on the left side of . or .* "

plz help me out! :(

Code:

---

table[row][col].list->adrs.row= crow4;
table[row][col].list->adrs.col= ccol4;

---

--
Mats

Heyyy guys!
now u go like: "oahhh not her againnn! with her stupid Q's!" ;) no don get me wrong this time! no more Q's on C! I'm done!:)
just wanted to say ThanK YoU to all of u guys that were of gr8 help to me in order to handle my proj! its over and I finally ended up with a mark of 90 out of 100 for the proj! :) I couldn't beleive that I finally did it, and that I did it this good! without u guys I couldn't go thru it! now I feel like how lucky I was to find this forum and be a member of it!

thanx alot
Bestest wishes...