Opening a text file in C

I have a program that is to open a text file. The code compiles, appears to validate as it should and so on....except:

If I used this code to open the file:

bank = fopen("C:\\tma307\\itembank.txt", "r");

it opens just fine.

but if I use:

bank = fopen(Bank, "r");

it won't open (I get a popup error that reads "Project1 has caused an error in CC3260MT.DLL. Project1 will now close")

Bank is the itemfile and bank is the pointer for my program.

What hapens is:

--I click on run (using Borland C++ Builder)

--It brings me to a menu in dos and prompts me to select an item

--I select v (for validate file) and it brings me to a blank dos screen where I am prompted to type in the disk file name.

--This is where I first noticed the problem. I don't even have to type in a disk file name to get my text file. I could just hit enter or happy new year for that matter.

I believe that as I have already declared the disk file name in the code, the program already knows where to go. But, if I make changes to the text file (and save them of course), it doesn't recognize anything different.

I have read many many articles on fopen etc. to try and figure this one out but have been unsuccessful.

Any suggestions would be greatly appreciated!

FILE * bank
bank = fopen("C:\\tma307\\itembank.txt", "r");

Should open the file for reading, so you may do whatever to it in your program later on.

Quote:

---

but if I use:

bank = fopen(Bank, "r");

it won't open (I get a popup error that reads "Project1 has caused an error in CC3260MT.DLL. Project1 will now close")

---

Of course you do. You aren't opening anything.

> bank = fopen(Bank, "r");
The only way this would work was if you were to do:
FILE * bank;
Bank = "C:\\tma307\\itembank.txt";
bank = fopen(Bank, "r");
Which confuses me just looking at it.
( then again, it's late )

What exactly are you looking to do?

Thanks for replying Shadow. Yes it is late and yes it is confusing.

I am opening the text file to validate certain conditions within the text. For example if a line reads more than 64 characters in length, return error reading "file length is too long - edit line length...".

So I believe that the correct way to open this file to validate it is:

FILE * bank;
bank = fopen(Bank, "r");

but it will only let me open the file with:

FILE * bank;
bank = fopen("C:\\tma307\\itembank.txt", "r");

I don't understand why I have to specify the path address there. I thought that I might have done something in main but all is in order there (I have compared my main.c with another classmate and they are exactly the same.

Perplexing isn't it!

Thanks for reply Salem. I agree that better variable names would have been ideal however they are part of my assignment of which I cannot change. I think they do that to keep us on our toes.

Anyway, here is more code:

int validate_file ( const char Bank[], int D_A[], int summary )
{
FILE * bank; // file pointer variable to item-file Bank

int err,
....

clrscr ();
bank = fopen("C:\\tma307\\itembank.txt", "r"); //

if...
{
printf("Error 7: ...");
...

hit_a_key("\n\n\n");

for( i=0; i!= EOF; ++i)
{
...and so on.

Given that function,
bank = fopen(Bank, "r");
seems OK

So the only question is
How are you calling this function?

I'm calling it as follows:

if(validate_file ( Bank, D_A, summary ) )
{
(bank != NULL)
{
printf("Error 7: Unable to open itembank file.\n");
printf("try to use the full name: C:\\TMA307itembank.txt\n");
}
else if (bank==NULL)
{
printf("The itembank file you have requested has opened successfully");
}
hit_a_key("\n\n\n");

for( i=0; i!= EOF; ++i)
{
...

> (bank != NULL)
This bank is not the same as the local variable bank in the validate_file function.

This bank is uninitialised

Sorry Salem, I missed a part of the code when I was pasting it. It should read:

if (bank != NULL)
...

Perhaps if you posted all your code, not just random snippets

Besides, doesn't matter how you wrote it, you still have a scope problem

In validate_file
bank = fopen("C:\\tma307\\itembank.txt", "r"); //

This is NOT the same bank as the one in the caller of validate_file

Yes, I agree that I have a scope problem. That's why I didn't want to post the whole code (it is very long).

My assignment specs state "Bank is the disk-name of an item-file to be validated"

So if I state Bank=fopen I get the following compiler error:

"can't modify a const object"

I know it must be quite difficult to give me advice when all the project facts are not know. Any suggestions on where I might get further info on "scope" issues or what else I might search under? I am sure that I have reviewed most of the sites on fopen etc.

Thanks

Perhaps it should be like this

Code:

---

if ( validate_file ( Bank, D_A, summary ) ) {
  bank = fopen(Bank, "r");
}

---

Thanks Salem but I tried that and it won't open the file for me. I just get a blank screen (yes I checked to make sure that there was indeed data in the text file).

Any other suggestions? Anyone?

I know there's a genius out there with the answer. Or any suggestions on where to look (ie a tutorial etc)?

Apart from the scope problem Salem has mentioned,

Can you use a break point?

If so check the contents in the string in the fopen() call. Make sure you are not trying to open

C:\\tma307\\itembank.txt
but
C:\tma307\itembank.txt

could be having a problem with the '\t' (which is a horz tab)

Quote:

---

int validate_file ( const char Bank[], int D_A[], int summary )
{

---

So given this...

Quote:

---

So if I state Bank=fopen I get the following compiler error:

"can't modify a const object"

---

You then do that?

Well no **** you can't modify 'Bank'. You've defined it as 'const char Bank[]'. Furthermore, if in fact you're doing it in this same function, 'Bank' is a character array. It is not a file pointer. FURTHERMORE, you can't assign ANYTHING to an array (other than a single element at a time) with the equals sign.

Quzah.

> That's why I didn't want to post the whole code (it is very long).

That's why there's a box at the bottom of the reply window called

"Attach file:"

I would suggest you use it.

I'm worried by the apparent size of this program, and the lack of understanding of some basic C programming principles.

I have attached a "portion" of the code however I don't think it would be enough to assist me any further.

It is discerning that you are "worried by the apparent size of this program, and the lack of understanding of some basic C programming principles". This is an introductory course of which I have been in for 2 months. Prior to that I had no programming experience at all.

Yes the program assigned is extensive but I have no control over that. I thought this forum was for beginners that are in need of help.

But thank you for all the assistance. It was appreciated.

> I have attached a "portion" of the code
Where?

> This is an introductory course of which I have been in for 2 months
Maybe so, but that doesn't mean that the tutor is setting the pace of the course at a level which you can cope with.

We've seen evidence of a lot of bad tutors on this board - from the homework they assign, to the "advice" they give.

How do you feel you are coping with the course in comparison to your class-mates?
If everyone is struggling, then the pace needs to be revised.

> I thought this forum was for beginners that are in need of help.
It is - but it is not a substitute for a well written tutorial, or a book or a lecture course. Most questions deal with fairly specific points, which are usually easy to answer.

The problem I was getting to was your question was turning into something much bigger and more significant that the usual "why doesn't this work".

>If everyone is struggling, then the pace needs to be revised.
The course has a 65% failure rate. I am working with others in this course and they are all coping at roughly the same rate I am.

>it is not a substitute for a well written tutorial, or a book or a lecture course

I agree and that is why this forum was my last resort. I can only imagine the number of bad tutors out there. We are basically on our own.

>The problem I was getting to was your question was turning into something much bigger and more significant that the usual "why doesn't this work".

I most definately agree.