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ft_strcmp.c
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ft_strcmp.c
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/* ************************************************************************** */
/* */
/* ::: :::::::: */
/* ft_strcmp.c :+: :+: :+: */
/* +:+ +:+ +:+ */
/* By: pbie <marvin@42.fr> +#+ +:+ +#+ */
/* +#+#+#+#+#+ +#+ */
/* Created: 2015/11/24 21:23:12 by pbie #+# #+# */
/* Updated: 2015/12/03 17:02:10 by pbie ### ########.fr */
/* */
/* ************************************************************************** */
#include "libft.h"
/*According to the man this function lexicographically compares the NULL
* terminated strings s1 and s2 that are passed into it's parameters. The
* function returns an integer greater than, equal to, or less than 0 depending
* on whether the string s1 is greater than, equal to, or less than string s2.
* The comparison is done using unsigned characters, so that '\200' is greater
* than '\0'.*/
int ft_strcmp(const char *s1, const char *s2)
{
/*We start by creating our counter variable i and making it an unsigned
* int in case we have a really long string. We then set it equal to 0 to
* place us at the start of our string in our loop.*/
unsigned int i;
i = 0;
/*Our while loop requres two conditions to be true for it to begin looping
* and to continue looping. We want the loop to happen as long as we have
* not reached the end of the string s1 AND we want the loop to happen only
* so long as the character at position i in s1 is the same as the character
* in postion i in s2. The second we find a difference in the string we want
* to compare the difference. */
while (s1[i] != '\0' && s1[i] == s2[i])
i++;
/*When we have either found a non matching character or we have reached the
* end of s1 we return the difference between the character in position i in
* s1 and teh character in position i in s2. NOTE: We are casting the
* characters into unsigned characters just like the man explained. The
* difference that is returned is based on the ascii table numerical value
* of the characters.*/
return ((unsigned char)s1[i] - (unsigned char)s2[i]);
}