Final Exam Review Question, please help

Another short response question I am working on and having trouble with. I can't catch why my logic is currently incorrect. It works well for n=5 but it does not work well for n=10.

NOTE: I am not suppose to use printf, but am using it so I can check my output.

Code:

---

/*Write a function that calculates and returns n factorial, where n is the input parameter.
You may assume that n is guaranteed to be positive. Note that n! = 1x2x3x…xn. (Note: You
 will get no credit on this question if you put a printf in this function.) Please fill out the function definition provided below:
*/
#include <stdio.h>

int main () {
       
int i=1, n=5, b=1, sum=0;

while(i < n){
b++;
sum+=i*b;
i++;
}
printf("%d\n", sum);

system("PAUSE");
return 0;


}

---

Quote:

---

Originally Posted by matthayzon89

It works well for n=5 but it does not work well for n=10.

---

What is not working for you? Do you have access to a debugger? That would undoubtedly be instructional for you to be able to step through a program line by line inspecting the variables as you go.

hmm, unfortunately I am not programming using GOOD software... I am using a 'free version' of a software that has limited access:/

Can someone help me out with the program above? I have spent wayy too much time on trying to figure out with no success, grrrr.

So get code::blocks then.

What's the program supposed to do?

Sorry, I forgot to include the instructions.

I edited a comment into the code.

Thanks.

Also, I am having a problem finding the answer to this question.
I would pick D,E, or B in that order.

Can someone help?


48) Which of the following is a standard C file in stdio.h?

A)output
B)stderr
C)input
D)ofp
E)None of the Above

Ok let's start by analyzing the requirements:

1) what is a factorial?

2) this factorial is to be a function, that is it needs to return the value of n factorial, so you can't write the logic for it in main.

Quote:

---

Originally Posted by matthayzon89

Also, I am having a problem finding the answer to this question.
I would pick D,E, or B in that order.

Can someone help?


48) Which of the following is a standard C file in stdio.h?

A)output
B)stderr
C)input
D)ofp
E)None of the Above

---

The phrasing is once again, "surprise surprise" very poor. However from the options he most likely wants you to answer B) stderr, which stands for standard error.

43) Which of the following function calls allocates memory dynamically?

A)getchar
B)malloc
C)fopen
D)getmem
E)None of the Above

Is the answer B?
I looked it up and it seems to be the answer, I just want to make sure, that there isnt an even MORE correct answer that falls into the "None of the Above" category.

No, finally this is a clear question. Yes, malloc is the answer.

Quote:

---

Originally Posted by claudiu

Ok let's start by analyzing the requirements:

1) what is a factorial?

2) this factorial is to be a function, that is it needs to return the value of n factorial, so you can't write the logic for it in main.

---

For example if n=5.

n! (<--factorial notation)= 1 x 2 x 3 x 4 x 5=120.


I know, you are correct.
I was just trying to test it out in MAIN so I understand what logic to apply to the function. Thats why I gave 'n' a value of 5, but n could be anything, and the factorial needs to basically multiply all the numbers upto n, incrementing by 1 each time.

42) How should the following struct definition be changed?

Code:

---

struct list {
  int data;
  struct list next;
};

---

A)change line 1 to struct *list {
B)change line 1 to struct[] list {
C)change line 2 to int *data;
D)change line 2 to int **data;
E)None of the Above


I would pick E).
I think nothing is wrong with this struct. I might be wrong. "struct list next;" <---declares a second struct with the type 'list' within the first struct (which includes the same types of data), am I right?
Either that, or Something IS wrong with the formatting of "struct list next;" and options C) and D)........... do not correct these errors.

So, either way, im going with E.

Quote:

---

Originally Posted by matthayzon89

42) How should the following struct definition be changed?

Code:

---

struct list {
  int data;
  struct list next;
};

---

A)change line 1 to struct *list {
B)change line 1 to struct[] list {
C)change line 2 to int *data;
D)change line 2 to int **data;
E)None of the Above


I would pick E).
I think nothing is wrong with this struct. I might be wrong. "struct list next;" <---declares a second struct with the type 'list' within the first struct (which includes the same types of data), am I right?
Either that, or Something IS wrong with the formatting of "struct list next;" and options C) and D)........... do not correct these errors.

So, either way, im going with E.

---

That's a bad idea. Can a thing hold another copy of itself inside it? Do you have room for another one of you inside you?

Yeah you are right, but isnt the answer E, anyways?

I noticed that its kind of like an 'infinite' declaration when you think about it, isnt it?

But answers C, and D, don't correct this error.

The question is what does that struct look like to you? What data structure does it resemble?

Quote:

---

Originally Posted by matthayzon89

Yeah you are right, but isnt the answer E, anyways?

I noticed that its kind of like an 'infinite' declaration when you think about it, isnt it?

But answers C, and D, don't correct this error.

---

Correct, and neither does B. So it's between A and E now, what do you think?

Please tell me that the answer is E for this question.

I hate asking so many questions but I never know with the way he puts his test together and he words his questions. I don't really have a lot of different ways to study besides reading the book and coding and asking questions.

35) Given that the array grid is defined as follows:

int grid[8][10];

which of the following two expressions are equivalent?

1) grid = 4;
2) *grid[2] = 4;
3) grid[2][0] = 4;
4) grid[2] = 4;

A)1 and 3
B)2 and 3
C)2 and 4
D)3 and 4
E)None of the Above

Quote:

---

Originally Posted by claudiu

Correct, and neither does B. So it's between A and E now, what do you think?

---

I thought it was E) but since u asked me again, I think I should have a REASON to believe it is A.

But I have created a structure where the declaration of the struct did not have a '*' near the name of the struct, so the only reason why 'A)' could be the answer is if the * is there to declare a struct that has other struct declarations within it.

I still think its E.

It's not E. First write down the type of each of the 4.

HINT: some are pointers, others are ints.

Quote:

---

Originally Posted by matthayzon89

I thought it was E) but since u asked me again, I think I should have a REASON to believe it is A.

But I have created a structure where the declaration of the struct did not have a '*' near the name of the struct, so the only reason why 'A)' could be the answer is if the * is there to declare a struct that has other struct declarations within it.

I still think its E.

---

But it can't be E because of what tabstop said.

The difference between A and E is that in A, the second member is a POINTER to another structure, not another structure itself.

To make an analogy, imagine these structures are mailboxes. The one you have in the question is a mailbox that when opened you figure out there's another mailbox of the same size in it. (kind of like using double bags).

The structure described by answer A is a mailbox that has inside it a little handwritten note that says :"check mailbox 101", therefore POINTING to another mailbox, sort of like a clue if you will.

Does that make sense?

What class is the exam for?

Intro to C Programming.

btw, I never took any programming classes or programming related classes b4 this class so all this material is completely new to me.

Quote:

---

Originally Posted by matthayzon89

Intro to C Programming.

btw, I never took any programming classes or programming related classes b4 this class so all this material is completely new to me.

---

This might sound weird but often times that is an advantage. You are doing well so far for a complete beginner. Not sure if this class is just an elective or not, but I hope to see you around the forums after you finish the class as well.

THANK YOU:)
That's nice to hear b/c most good programmers are too 'smart' when I ask them questions and I don't notice any progress b/c it seems like everything I think I know about programming, its never on point, you know what I mean? There is always a 'more' correct answer, which makes me feel like there is little to no progress, but I am finally beginning to feel like I have learned something, now I am kind of putting together all the pieces of the puzzle.

IT might seem like my professor is NOT cool for asking such tricky questions but his teaching methods are very rewarding to the students, so I am most definitely not mad at him for those tricky questions, I just don't enjoy trying to 'tackle' them b/c answers don't POP out at you like they normally do when you take a multiple choice test.


TRUST ME! I will be around these forums for a longgggggg time.

I enjoy, programming a lot! I love how it makes you use you brain and logic. It's challenging and rewarding. I hope to continue to grow as programmer.

Next year I am probably going to start learning the basics of Java... and I hope to learn C++ too, I heard there a lot of similarities and that C++ is a lot better.

16) Strictly speaking, how many values can a function return?

A)2
B)5
C)10
D)more than 100
E)None of the Above

I would assume that a function can return more then 100 values. (D).

b/c isn't a function kind of like MAIN in that it has most if not all the capabilities that main has?

So basically if I can figure out more then 100 different values in main then there is no reason why I can figure those same values out in a function and the return them to main, am I correct?

Quote:

---

Originally Posted by matthayzon89

THANK YOU:)
That's nice to hear b/c most good programmers are too 'smart' when I ask them questions and I don't notice any progress b/c it seems like everything I think I know about programming, its never on point, you know what I mean? There is always a 'more' correct answer, which makes me feel like there is little to no progress, but I am finally beginning to feel like I have learned something, now I am kind of putting together all the pieces of the puzzle.

IT might seem like my professor is NOT cool for asking such tricky questions but his teaching methods are very rewarding to the students, so I am most definitely not mad at him for those tricky questions, I just don't enjoy trying to 'tackle' them b/c answers don't POP out at you like they normally do when you take a multiple choice test.

---

I know what you mean. Programmers are usually very jumpy about what's better and what's not, mostly because efficiency and correctness are a big deal when it comes to software. Your advantage is that you have the right attitude, you listen, and you ask questions and are not pompous about doing it. Remember, the only stupid question is the question you didn't ask, when you were not sure.

Quote:

---

Originally Posted by matthayzon89

16) Strictly speaking, how many values can a function return?

A)2
B)5
C)10
D)more than 100
E)None of the Above

I would assume that a function can return more then 100 values. (D).

b/c isn't a function kind of like MAIN in that it has most if not all the capabilities that main has?

So basically if I can figure out more then 100 different values in main then there is no reason why I can figure those same values out in a function and the return them to main, am I correct?

---

Well, MAIN is a function. It's just a special function because that's where everything starts, where the rest of the functions get called.

In terms of the actual question I believe it's E because a function can only return one value. You are reasoning correctly in that, a function can process multiple variables inside it, but remember you can only have one thing next to your return statement. It's the term value that is tricky here, because theoretically you can return an array that contains more than one value. However even then, in your return statement you are basically returning one thing, the pointer to the start of your array.

Can someone please explain how the value of sum=29 at the end of this nested loop?

I was trying to track it, but I think the continue is throwing me off.

I added comments to the code below stating my logic for the first 'round' of tracking... surely, I went wrong somewhere...

Code:

---

int i=0, j=0, sum=0;
while (i < 3) {  //0 < 3
  while (j < 6) { //0 < 6
    sum = sum + j;  //0+0=0
    j++; // j=1
    if (sum > 10)  //this condition is NOT met so 'J' is incremented again, right? now j=2
      continue;
    j++;
  }
  i++; //this is not incremented in the first round is it?
  j=i;
}

---

Quote:

---

Originally Posted by claudiu

Well, MAIN is a function. It's just a special function because that's where everything starts, where the rest of the functions get called.

In terms of the actual question I believe it's E because a function can only return one value. You are reasoning correctly in that, a function can process multiple variables inside it, but remember you can only have one thing next to your return statement. It's the term value that is tricky here, because theoretically you can return an array that contains more than one value. However even then, in your return statement you are basically returning one thing, the pointer to the start of your array.

---

cant you write a function similar to this????
(this is probably a stupid example...but I thought I would be able to pass more then 1 value from a function)


I think I see the logic behind this....
A function is suppose to figure out something (one thing) so if I wanted a function to pass more the one thing I need more then 1 function.

If the example below is incorrect, it is because the computer tries to come up with 1 correct value to pass to main, so if the conditions inside the if statement are NOT met it keeps going until it IS met and as SOON as a condition is met then it returns the first value after the true if statement, right?

Code:

---


int x=1, y=5;

x=5+x;
if(x==5)
return 0;
if(x==3)
return 1;

y=3+y;
if(y==7)
return 2;
else
return 5;

---

You seem to be tracking values correctly so far. Just ignore i++ and j=i; until j < 6 is false. until j = 6 in the first run everything happens in the inner loop. So what's the value of sum after the inner loop gets executed the first time?

Quote:

---

Originally Posted by matthayzon89

cant you write a function similar to this????
(this is probably a stupid example...but I thought I would be able to pass more then 1 value from a function)

Code:

---


int x=1;

x=5+x;
if(x==5)
return 0;
else
return 1;

---

---

Oh ok, I see what you are saying. Well that's why I think the question is a little vague. If it means : "how many different values can a function return" then your example proves that it could be as many as you wanted to. You could have a million conditions in there with a million different return statements.

If the question states : "how many values does it actually return" it's still one. Because it can't return both 0 and 1, just one of them, does that make sense?

Yeah that definitely makes sense, I edited what you quoted, take a look.

Thanks for all your help man, you've been around since I started this thread.

Quote:

---

Originally Posted by matthayzon89

Yeah that definitely makes sense, I edited what you quoted, take a look.

Thanks for all your help man, you've been around since I started this thread.

---

Yeah, that's basically what I meant by "you can return any number of different values".

Quote:

---

Originally Posted by claudiu

You seem to be tracking values correctly so far. Just ignore i++ and j=i; until j < 6 is false. until j = 6 in the first run everything happens in the inner loop. So what's the value of sum after the inner loop gets executed the first time?

---

hmm, I keep getting it wrong, even though I track it like you said.

first time its 0 second time its 2 third time its 6..

Right. Then move on to the outer loop. (i.e. i++ and j = i) and see what the sum is after the inner while completes with these values. Then do the same for the third round. After that, i will be 3 so the outer while will exit.

Quote:

---

Originally Posted by claudiu

Right. Then move on to the outer loop. (i.e. i++ and j = i) and see what the sum is after the inner while completes with these values. Then do the same for the third round. After that, i will be 3 so the outer while will exit.

---

Oh now I see...
Thats a lot more tracking then I expected from one problem if you ask me lol.

Quote:

---

Originally Posted by matthayzon89

Oh now I see...
Thats a lot more tracking then I expected from one problem if you ask me lol.

---

Yes, I will agree that for an intro level class this could be considered one of the trickier problems. But if you detach yourself from it for a second and just think about it, it's all about tracking the values throughout each instruction. There's nothing bizarre or complex happening there. If you just write them down on a piece of paper and keep updating the values you end up with the answer. The trick is not to get sidetracked and forget where you were or what the last value of some variable was.

Quote:

---

Originally Posted by matthayzon89

42) How should the following struct definition be changed?

Code:

---

struct list {
  int data;
  struct list next;
};

---

A)change line 1 to struct *list {
B)change line 1 to struct[] list {
C)change line 2 to int *data;
D)change line 2 to int **data;
E)None of the Above


I would pick E).
I think nothing is wrong with this struct. I might be wrong. "struct list next;" <---declares a second struct with the type 'list' within the first struct (which includes the same types of data), am I right?
Either that, or Something IS wrong with the formatting of "struct list next;" and options C) and D)........... do not correct these errors.

So, either way, im going with E.

---

Wait. What? Why does everybody think that A is the right answer? Of course A is not correct. I mean, what the heck would the following mean:

Code:

---

struct *list {
  int data;
  struct list next;
};

---

Makes no sense...

So the right answer *IS* E.


(Actually, it seems only claudiu thinks so, but the rest remains silent...)

Oh my bad. Of course you are correct. I thought it was referring to the 3rd line in the text. My apologies.

Quote:

---

Originally Posted by claudiu

Oh my bad. Of course you are correct. I thought it was referring to the 3rd line in the text. My apologies.

---

I figured ;-). It's not too strange, because a properly asked question would actually have a solution. Or at least two different solutions for "Nothing has to be changed" and "Your options are just plain wrong".
Another fairly bad question in my opinion, as both those with the right answer as the most usual wrong answer ("this is fine") will be right.

I wouldn't be surprised if the teacher thought A was the correct answer at the time he wrote it.

Yeah to be honest at least half of his questions were suspicious; sometimes the question is not "tricky" like Matt called it but rather confusing or unintentionally misleading, even to a more experienced C programmer.

Quote:

---

Originally Posted by claudiu

Yeah to be honest at least half of his questions were suspicious; sometimes the question is not "tricky" like Matt called it but rather confusing or unintentionally misleading, even to a more experienced C programmer.

---

Agreed. To the question of how many values a function can return, I'd answer "None of the above", because it can return 0, 1, 2, .....
That's a fair share of values. In fact, you can return as many as you want, theoretically.

That's how I first interpreted the question. And yet again, another question where "E" can very well be said to be correct.

Quote:

---

Originally Posted by EVOEx

(Actually, it seems only claudiu thinks so, but the rest remains silent...)

---

So... anyone who has posted in this thread but fails to keep up with it is complicit in a mistake made by anyone who posts in this thread? ;)

Quote:

---

Originally Posted by EVOEx

To the question of how many values a function can return, I'd answer "None of the above", because it can return 0, 1, 2, .....
That's a fair share of values. In fact, you can return as many as you want, theoretically.

That's how I first interpreted the question. And yet again, another question where "E" can very well be said to be correct.

---

I think that claudiu's answer is correct: strictly speaking, a function may return at most one value. If we remove the "strictly speaking", then perhaps we could count returning a pointer to the first element of an array as returning more than one value, or the use of out parameters as another way to return more than one value.

Quote:

---

Originally Posted by laserlight

So... anyone who has posted in this thread but fails to keep up with it is complicit in a mistake made by anyone who posts in this thread? ;)


I think that claudiu's answer is correct: strictly speaking, a function may return at most one value. If we remove the "strictly speaking", then perhaps we could count returning a pointer to the first element of an array as returning more than one value, or the use of out parameters as another way to return more than one value.

---

What a relief. So I am not crazy after all, although I have been up all night working and probably left somewhat offside by Matt's questions. :)

Quote:

---

Originally Posted by laserlight

So... anyone who has posted in this thread but fails to keep up with it is complicit in a mistake made by anyone who posts in this thread? ;)

---

Nah, first I thought there were several that agreed with this answer, but I misread something :P. I only figured after posting :P. But I did expect there would've been someone who'd spotted the mistake.

Quote:

---

Originally Posted by laserlight

I think that claudiu's answer is correct: strictly speaking, a function may return at most one value. If we remove the "strictly speaking", then perhaps we could count returning a pointer to the first element of an array as returning more than one value, or the use of out parameters as another way to return more than one value.

---

I didn't mean an array as several values, I meant that 0 and 1 itself are different values, for instance. Let's say a function returns true or false; those are two values it can return. A value that returns an integer can return INT_MAX - INT_MIN separate values. Of course, it simply depends on the interpretation of the word "value". But don't you consider 1 to be a value? And 2? And 3?
If the question was how many "variables" can a function return, then I agree, it can only be one.

Quote:

---

Originally Posted by EVOEx

I didn't mean an array as several values, I meant that 0 and 1 itself are different values, for instance. Let's say a function returns true or false; those are two values it can return. A value that returns an integer can return INT_MAX - INT_MIN separate values. Of course, it simply depends on the interpretation of the word "value". But don't you consider 1 to be a value? And 2? And 3?
If the question was how many "variables" can a function return, then I agree, it can only be one.

---

Ah, I see what you mean. But it is still true that a function can only return at most one value. You cannot return both 1 and 2 at the same time. However, if you say that because 1 is a possible value that could be returned, and 2 is another possible value that could be returned, thus the function could return more than one value, then I propose to you that here is a function that returns two variables:

Code:

---

int foo(void)
{
    int n = 1, m = 2;
    if (rand())
    {
        return n;
    }
    else
    {
        return m;
    }
}

---

Quote:

---

Originally Posted by laserlight

Ah, I see what you mean. But it is still true that a function can only return at most one value. You cannot return both 1 and 2 at the same time. However, if you say that because 1 is a possible value that could be returned, and 2 is another possible value that could be returned, thus the function could return more than one value, then I propose to you that here is a function that returns two variables:

Code:

---

int foo(void)
{
    int n = 1, m = 2;
    if (rand())
    {
        return n;
    }
    else
    {
        return m;
    }
}

---

---

Yes, I do understand your point (I did when I said I considered E to be a legal answer), but my point was that yet again the question can - in my opinion - be interpreted to have two legal answers.
See, the function you wrote, I consider, can return two different values. Either 1 or 2. Of course, it can only return one value at a time.
So it's again a fairly badly asked question, in my opinion. Don't you agree that the interpretation I was talking about, where E is the answer, is actually fine as well?

The better question would be "How many variables can a function return", IMHO.

Quote:

---

Originally Posted by EVOEx

Don't you agree that the interpretation I was talking about, where E is the answer, is actually fine as well?

---

The problem is, using your interpretation, any member of the set of non-zero integers, and sets thereof, is a correct answer. Thus, all the answers are correct. You have pointed this out yourself, so a choice of E is no better than a choice of A, B, C or D.

Quote:

---

Originally Posted by EVOEx

The better question would be "How many variables can a function return", IMHO.

---

If by variable you mean an identifier for an object, then functions do not return variables. You would have to use a macro to "return" a variable (but then strictly speaking, macros don't return anything).

Maybe specifying "given a particular control path in the execution of a function" would be clearer, but such a technical phrase itself may need to be clarified to novices.

O_o

"How many values can be returned to a calling function as part of any `return' statement?"

*shrug*

It needs work.

I'd argue that a function can return exactly as many values as the designer deems necessary.

Soma

Quote:

---

Originally Posted by laserlight

The problem is, using your interpretation, any member of the set of non-zero integers, and sets thereof, is a correct answer. Thus, all the answers are correct. You have pointed this out yourself, so a choice of E is no better than a choice of A, B, C or D.


If by variable you mean an identifier for an object, then functions do not return variables. You would have to use a macro to "return" a variable (but then strictly speaking, macros don't return anything).

Maybe specifying "given a particular control path in the execution of a function" would be clearer, but such a technical phrase itself may need to be clarified to novices.

---

Hmmm actually I consider that it can return an infinite number of values, then, so the best answer would actually be "more than 100". On the other hand, if you consider it using "the right" interpretation, some functions can return no values, namely the void variables. So the answer would actually be "sometimes 0, sometimes 1" in that case. Again, none of the above.

Yes, I AM being pedantic, as I consider it a must for professors to word their wishes clearly.

You're right that "variable" isn't the right term here, either. But then again, the question entirely makes no sense. Anybody who would understand the question and knows even the slightest amount of C would be able to answer the question properly. Unless he misunderstood the question.

But "given a particular control path in the execution of a function" isn't quite right either. Consider the function rand(). It has one control path, but still returns different things...

If I were the professor, I'd drop this question entirely.

This is a stupid question unreleated to programming but I cannot find it anywhere! It is SO simple.
I used to know how to do this in seconds when I took algebra... however, I forgot.

This is a component of one of the problems I need to know on my final...

I know that once I have (k+2)(2k+3) I can simply multiply and get 2k^2+7k+6.

But if (k+2)(2k+3) was NOT given, how would I extract it from 2k^2+7k+6??

I remember there was a simple trick to this, however, I forgot.

Can someone please help?

idk where else to look for an answer to this I tried the yahoo answers with no success:/

Thanks!

Well, one way is to solve the equation and get two distinct values for k.
Solving it gives us the roots -1.5 and -2, which can be written as (k + 1.5)(k + 2) or (2k + 3)(k + 2) if you will.
There is a connection between the numbers, which you can extract if you're good, but meh, I can never remember.

This is a basic quadratic. You can wikipedia how to find the solutions to this.

Quadratic equation - Wikipedia, the free encyclopedia

Can someone please help me understand why the output is: 99 c for the code below?

I know that %d<----- gets its value from the 'anscii chart' so a=97 b=98 and c=99, so that makes sense, but I thought %c is a mistake and it should be %s for a char, so I dont get why %c still works....

Code:

---

printf("%d %c",'c', 'c');

---

Well the char type is actually the ascii code for the char it contains. So if you print a char using %d it will print it's corresponding ASCII code which, like you observed is 99. The second print prints it as a character, simply 'c'.

I know that c prints out, but will %c always work to print out a char?

I thought that hte correct type for char is %s.. thats why I was confused as to WHY it actually prints out 'c' when the type is incorrect...

You know what I mean?


P.S
My final is tomorrow, im starting to get stressed lol...

Also,
Can someone help me understand what is this question asking exactly?
I know that j*=j+3 is the same as j=j*k+3; (A) but the wording of this question threw me off a bit...

9) Given that the precedence of *= is lower than +, what is the equivalent statement to j*=k+3;?

A)j = j*k + 3;
B)j = j(k+3);
C)j = j*(k+3);
D)j = j*k*3;
E)None of the Above

Quote:

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Originally Posted by matthayzon89

I know that c prints out, but will %c always work to print out a char?

I thought that hte correct type for char is %s.. thats why I was confused as to WHY it actually prints out 'c' when the type is incorrect...

You know what I mean?


P.S
My final is tomorrow, im starting to get stressed lol...

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%s is for strings. %c is for chars.

Quote:

---

Originally Posted by matthayzon89

Also,
Can someone help me understand what is this question asking exactly?
I know that j*=j+3 is the same as j=j*k+3; (A) but the wording of this question threw me off a bit...

9) Given that the precedence of *= is lower than +, what is the equivalent statement to j*=k+3;?

A)j = j*k + 3;
B)j = j(k+3);
C)j = j*(k+3);
D)j = j*k*3;
E)None of the Above

---

j<operation>= something means j = j <operation> something;

I'll let you figure out the rest.

A char can never be a string - although a string with just two char's, when printed, will look just like a char.

A char: 'a'.
A string: "a\0"

a char can never be a string because it doesn't have enough room for the end of string marker: '\0', that would elevate it to string status.

What is this: ABCDEFGHI ?

Not a string!

Without the char str[] = "ABCDEFGHI" double quotation marks, it will get no end of string marker, and be just a bunch of chars, and not a string, unless a kind programmer adds it later.

Since j *= k+3 is shorthand for j = j * k+3, if the two aren't equivalent, C is in trouble.

Can someone please help me understand what a this questions is actually asking? mpre specifically, what is a 'keyword' in c programming?

7) Which of the following is NOT a keyword in C?

a) scanf b) float c) while d) break e) struct

Is this a correct way to generate a random number between -19 and 39?

ran()%39–19

Quote:

---

Originally Posted by matthayzon89

Can someone please help me understand what a this questions is actually asking? mpre specifically, what is a 'keyword' in c programming?

7) Which of the following is NOT a keyword in C?

a) scanf b) float c) while d) break e) struct

---

A keyword is a reserved word used by the language that you cannot use as a variable or function name. What do you think is the right answer given this information?

Can someone please explain why the answer in this case is C)?

I looked it up, but it does not make sense to me b/c getchar() gets a character which is not an integer... also, why is it void? (I know what void is, but why is it void in this case?)

12) Which of the following is the proper function prototype for the getchar function?

a) char getchar(char c) b) void getchar(char c)
c) int getchar(void) d) int getchar(char c)
e) char getchar(char c, int n)

Quote:

---

Originally Posted by matthayzon89

Is this a correct way to generate a random number between -19 and 39?

ran()%39–19

---

rand()%39 returns numbers in the 0-38 range. Generally rand%n returns numbers in the range (0 - n-1).

Quote:

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Originally Posted by claudiu

A keyword is a reserved word used by the language that you cannot use as a variable or function name. What do you think is the right answer given this information?

---

Oh, thanks for clarifying.

I would go with D)Break. b/c breaks are usually used in loops and I don't see how using it as a name of a variable or function would throw the computer off..
WOW, I am actually wrong, I just tried it, and the correct answer is scanf.... do you know why that is? I find it hard to think about why scanf is okay to use as avariable name and everything else isnt...

Quote:

---

Originally Posted by matthayzon89

Can someone please explain why the answer in this case is C)?

I looked it up, but it does not make sense to me b/c getchar() gets a character which is not an integer... also, why is it void? (I know what void is, but why is it void in this case?)

12) Which of the following is the proper function prototype for the getchar function?

a) char getchar(char c) b) void getchar(char c)
c) int getchar(void) d) int getchar(char c)
e) char getchar(char c, int n)

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These are all stupid answers to a stupid question Matt. Think about it, you can write a getchar function using any of these prototypes and even a thousand other variants. It just happens that one of the getchar() functions defined in the C libraries resembles answer C. This is not reason however that the other answers are wrong.

Quote:

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Originally Posted by matthayzon89

Oh, thanks for clarifying.

I would go with D)Break. b/c breaks are usually used in loops and I don't see how using it as a name of a variable or function would throw the computer off.

---

Try declaring a variable called:

int break;

Quote:

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Originally Posted by Adak

A char can never be a string - although a string with just two char's, when printed, will look just like a char.

---

A single character with the value of '\0' is considered a valid string:

Code:

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char c = '\0';

printf("len is: %d\n", strlen( &c ) );

---

:)


Quzah.

Quote:

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Originally Posted by quzah

A single character with the value of '\0' is considered a valid string:

Code:

---

char c = '\0';

printf("len is: %d\n", strlen( &c ) );

---

:)


Quzah.

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lol. True that, however come on Quzah, although you "say it how it is" even you don't believe that this information is going to help out a beginner understand what the heck is going on :).

Quote:

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Quote:
Originally Posted by Adak View Post
A char can never be a string - although a string with just two char's, when printed, will look just like a char.

A single character with the value of '\0' is considered a valid string:

Code:

---


char c = '\0';
printf("len is: %d\n", strlen( &c ) );

---

---

That doesn't make c a valid string.

Print out c:

Code:

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printf("%c", c);

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and I get (null).

Print out strlen(c):

Code:

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printf("%d", strlen(c));

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and you'll get 0.

Null means nothing, and strlen doesn't count the end of string char - so neither do I.

Quote:

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Originally Posted by Adak

That doesn't make c a valid string.

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By definition ("contiguous sequence of characters terminated by and including the first null character"), I think that one can consider it a string.

Quote:

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Originally Posted by Adak

Print out strlen(c): (...) and you'll get 0.

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Actually, that probably results in undefined behaviour. Notice that quzah called strlen(&c). The reason is that strlen() requires a pointer to the first character of a string as its argument.

Quote:

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Originally Posted by Adak

strlen doesn't count the end of string char - so neither do I.

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What do you mean? If you used strlen(&c) you should get 0. Likewise, if you used strlen("") you should get 0. So, "" is not an empty (as in zero length) string?

Not according to your definition:

Quote:

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By definition ("contiguous sequence of characters terminated by and including the first null character"), I think that one can consider it a string.

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One character won't do unless you can show they have a lisp. :p

Quote:

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Originally Posted by Adak

Not according to your definition:
(...)
One character won't do unless you can show they have a lisp.

---

So, how many brains do you have? One won't do unless you have a lisp ;)

In other words, the plural here does not exclude the singular.

EDIT:
Consider:

Quote:

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Originally Posted by C99 Section 6.4.5 Paragraph 2

A character string literal is a sequence of zero or more multibyte characters enclosed in double-quotes, as in "xyz".

---

Therefore, "" is a string literal. But, according to your interpretation of the plural, "" is not a string literal. This is a contradiction, therefore your interpretation is incorrect.

My compilers are certainly not C99. :D

One of them predates the standards as we know them now, adhering to the AT&T standard.

When strlen reports '\0' as a one character string, I'll go along with it, as well. Until then, we'll just have to agree to disagree.

Quote:

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Originally Posted by Adak

My compilers are certainly not C99.

One of them predates the standards as we know them now, adhering to the AT&T standard.

---

I believe that they are all the same in this respect. Otherwise, it means that the compiler does not accept "" as an empty string.

Quote:

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Originally Posted by Adak

When strlen reports '\0' as a one character string, I'll go along with it, as well.

---

You're missing the point: '\0' is a null character, of type int. However, it can be interpreted as an empty string, thus it is a string. This whole issue is academic though: if you really do want an empty string, you might as well go with "" instead of taking the address of a char whose value is '\0'.

Quote:

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Originally Posted by claudiu

These are all stupid answers to a stupid question Matt. Think about it, you can write a getchar function using any of these prototypes and even a thousand other variants. It just happens that one of the getchar() functions defined in the C libraries resembles answer C. This is not reason however that the other answers are wrong.

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There are only two prototypes that potentially make sense, so I wouldn't say it's stupid.

Quote:

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Originally Posted by matthayzon89

Oh, thanks for clarifying.

I would go with D)Break. b/c breaks are usually used in loops and I don't see how using it as a name of a variable or function would throw the computer off..
WOW, I am actually wrong, I just tried it, and the correct answer is scanf.... do you know why that is? I find it hard to think about why scanf is okay to use as avariable name and everything else isnt...

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A keyword is a reserved word in the language. It cannot be used in variable names, function names, etc. However, scanf is a function. Do you see the difference?

It really doesn't matter what your definition of plural is, because if I ask: "How many characters are in that string?", "Zero" is a grammatically correct answer. :)

And yes, just a nul character is a valid string. Otherwise, you could never do this:

Code:

---

char foo[ BUFSIZ ] = {0};
...
strcat( foo, "if foo is not a string, this is invalid" );

---

Quzah.

Quote:

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Originally Posted by laserlight

'\0' is a null character, of type int. However, it can be interpreted as an empty string, thus it is a string. T

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According to the rules of logic, the above does not make sense. It is an honest mistake though.

Think about it...

Does an empty string=string?

Does a string that is NOT there= string?

If A=(empty set) does A contain a number?

Code:

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NOTE:empty set != 0.

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:)