strrev! whats wrong?

[Silverdream]

Well here is my program to reverse a string.

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

void xstrrev(char *s, char *s1);

int main()
{
	char s[]="srini";
	char s1[10];

	xstrrev(s,s1);

	return 0;
}

void xstrrev(char *s, char *s1)
{
	int len,i;
	len=strlen(s);

	while(*s!='\0')
		s++;

	s--;

	for(i=len;i>=0;i--)
	{
		*s1=*s;
		len--;
		s--;
		s1++;
	}
	*s1='\0';
	printf("%s",*s1);
}

Please tell where am i doing wrong?

[Silverdream]

Well i got it working. Here is the code

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

void xstrrev(char *s);

int main()
{
	char s[]="srini";


	xstrrev(s);

	return 0;
}

void xstrrev(char *s)
{
	int len,i;
	char s1[10],*s2;
	s2=s1;
	len=strlen(s);

	while(*s!='\0')
		s++;

	s--;

	for(i=0;i<len;i++)
	{
		*s2=*s;
		s--;
		s2++;
	}
	*s2='\0';
	printf("%s",s1);
}

But i still want to know why the previous code didnt work?
Please help

[foniks munkee]

the code :

while(*s!='\0')
s++;
s--;

Doesn't actually do anything. Once it has executed the s is still pointing to the same place in memory. Try actually printing the value of s and its location in memory along side it and you can see.

The code below also achieves what you were looking for:


void xstrrev(char *s, char *s1)
{
int len,
int i;

len= (strlen(s) -1); // To ensure you don't start on NULL

for(i= 0; i <= len ;i++)
{
*(s1 + i)=*(s + (len - i));
}
*(s1 + i)='\0';

printf("%s\n", s1);
}

[foniks munkee]

Actually .. Looking at this again I could be wrong .. Anyone care to shoot me down!

That while loop will actually reference a different value.. Oops.