Reverse function

[COKEDUDE]

Can someone please explain why this function will not compile.

#include <stdio.h>
#include <string.h>
#include <ctype.h>

// This function determines if a string is a palindrome.
/* This function reverses the characters in the string
 * passed by the caller. */
void is_palindrome (char* string)
{
    int i;
    int length = strlen(string);
    int half_way = length/2;

    printf ("Function reverse called for string %s\n",
               string);

    for (i = 0; i < half_way; i++)
    {
        swap (&string[i], &string[length-1-i]);
    }
}

int main(void)
{
    char input[1000] = "";
    printf ("Enter a message: ");
    fgets(input, 1000, stdin);
    input[999] = 0;
 
    is_palindrome(input);

    return 0;
}

[BestJewSinceJC]

Where does that swap function come from. I'm betting that neither ctype.h, string.h, nor stdio.h define a function which matches the method header that you attempted to use in your call to swap().

[COKEDUDE]

Where does that swap function come from. I'm betting that neither ctype.h, string.h, nor stdio.h define a function which matches the method header that you attempted to use in your call to swap().

I thought the swap function was defined in #include <stdio.h>. Is that correct?

[BestJewSinceJC]

stdio.h defines functions used for input and output. Does swap() seem like such a function? And you can google as well as I can. Is swap defined in stdio.h?

[WaltP]

Can someone please explain why this function will not compile.

It would be better if you explain why you think it doesn't compile. I assume the compiler says something to lead you to that conclusion. By posting what it says, we can tell you exactly why, and we won't have to guess.

[Narue]

>I thought the swap function was defined in #include <stdio.h>.
You guessed wrong[1]. Maybe instead of thinking from a position of ignorance, you should do some research and enlighten yourself.

[1] In some parallel universe where the standard C library contains a swap function, it would most likely be in <stdlib.h>.

[urbangeek]

[1] In some parallel universe where the standard C library contains a swap function, it would most likely be in <stdlib.h>.

you meant there's no swap function in standard C library right?(oh..my bad english...:-/) i didn't find anything in the link or google too..

input[999] = 0;

Also, why this is needed?

[Narue]

>you meant there's no swap function in standard C library right?
Yes.