subtraction of two pointers..

[transgalactic]

what is the meaning of subtraction of two pointers??

return str-temp

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

int what(char *str, char ch){	
char *temp;
for( temp = str; *str; str++)
if(*str != ch) *temp++ = *str;
	*temp = ‘\0’;	
	return str-temp;
}

void main(){
	char string[ ]= "xbxbabsxdx";

	printf(“result = %d\n”, what(string, ‘x’));
	puts(string);
}