Writing the fgets function, how do I return a char pointer?

Quote:

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Originally Posted by master5001

Normally, none of us condone just "using" someone else's code. But since Microsoft does it all the time... then sues the rightful author for ownership, why the hell not do it back to them.

Just a word of caution: if this is a homework assignment, you should not hand in code that was written by Microsoft (even if it has been slightly altered by yours truly) since it is unethical. If you do, even if you give proper due credit to M$ and me, your teacher will probably not be all too thrilled.

Otherwise, no problem bud.

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Funny you brought in the MS code, I'm running Ubuntu for my development environment.
I'm still trying to rewrite it in terms of the array/pointer method I was doing with the original code. The Kernighan and Ritchie book does it this same way except without the stdarg library. It's not for an assignment, I just took up C since it's a useful skill to have and decided to do this as a pointers excercise.

Heh... if you knew me well you'd realize that it is usually not an accident when I use MS code. You can download the source for all the standard C libraries, ya know. Or if its an issue of just wanting a quick fix, you can always just google something like "printf.c" and you'll magically have the source code that you wanted. Though doing it this way isn't necessarily going to produce the best code. But with a C standard function like fgets(), you shouldn't end up with something too convoluted.

Quote:

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Originally Posted by master5001

Heh... if you knew me well you'd realize that it is usually not an accident when I use MS code.

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Now you've bated my curiosity and the site doesn't even have a list user's posts feature.

Anyway, I get a "can't turn pointer into integer" error at compile time for the commented out code:

Code:

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char *fgets1(char *str, int size, FILE *file)
{
  char *str2;
  str2 = str;
  /*  *str2 = malloc(sizeof(*str2) * size); */
    while(--size > 0 && (*str2++ = getc(file)) != EOF || *str2 != '\n'){}
  *str2 = '\0';
  return str2;
}

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I realize it's not necessary to malloc here, but I don't get why the int error comes up...

It is because you should not be dereferencing str2. Get rid of the * in front of it.

You can click a user's name and then view all their posts from their profile, actually. Though I think they only archive back to like 3 years ago. And I have been a member for 7 years...

Your posts.

To clarify what Master5001 is saying: "*str2" is of the type char, which the compiler sees as a integer compatible type. malloc returns void *, which is a pointer. So you are trying to allocate memory to a pointer.

Your current fgets fails if you have an EOF at the first attempt to read something [which usually happens at the end of a file, when you've read the very last bit of data]. You should return NULL at that point.

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Mats

Quote:

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Originally Posted by matsp

To clarify what Master5001 is saying: "*str2" is of the type char, which the compiler sees as a integer compatible type. malloc returns void *, which is a pointer. So you are trying to allocate memory to a pointer.

Your current fgets fails if you have an EOF at the first attempt to read something [which usually happens at the end of a file, when you've read the very last bit of data]. You should return NULL at that point.

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Mats

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How come in the tutorial they do it with a dereference or is that a typo...

Second to last code block:

http://www.cprogramming.com/tutorial/c/lesson6.html

sizeof expressions are not executed; so yes, you can create arrays, for example, like

numbers = malloc(sizeof *numbers * 10);

with little consequence. This is correct because the compiler can deduce the resulting type of an expression like *ptr