C : strrchr() analyze and example get self executable directory function.

strrchr() function will return a pointer to the last occurrence.

	char a[] = "abc123";
	char *b = strrchr(a, '1');
	printf("%s\n", b); // 123
	printf("%d\n", b); // pointer to '1', in my machine is 229315
	printf("%d\n", a);// pointer to 'a', in my machine is 229312

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Another example is modify from Advanced Linux Programming chapter 11.We can get a sub-sting without the occurrence with sub two pointer.

	#include <errno.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>
	int main(int argc, char* argv[])
	{
	int rval;
	char link_target[1024];
	char* last_slash;
	size_t result_length;
	char* result;
	/* Read the target of the symbolic link /proc/self/exe. */
	rval = readlink ("/proc/self/exe", link_target, sizeof (link_target));
	printf("%s\n", link_target);
	if (rval == -1)
	/* The call to readlink failed, so bail. */
	abort ();
	else
	link_target[rval] = '\0';/* NUL-terminate the target. */
	/* We want to trim the name of the executable file, to obtain the
	directory that contains it. Find the rightmost slash. */
	last_slash = strrchr (link_target, '/');
	if (last_slash == NULL || last_slash == link_target)
	/* Something strange is going on. */
	abort ();
	/* Allocate a buffer to hold the resulting path. */
	result_length = last_slash - link_target ;
	result = (char*) malloc (result_length + 1);
	/* Copy the result. */
	strncpy (result, link_target, result_length);
	result[result_length] = '\0';
	printf("%s\n", result);
	return 0;
	}

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Ref:
   1. http://www.cplusplus.com/reference/cstring/strrchr/
   2. Advanced Linux Programming by Mark Mitchell, Jeffrey Oldham, and Alex Samuel www.newriders.com