gistfile1.c

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
char *str_replace(char *search , char *replace , char *subject);

int main()
{
	char *a = "http://www.google.com.www.abcd.com.www.sadasdasd.www.";
	
	char *c = str_replace("http://" , "" , a);
	c = str_replace("www." , "REPLACEMENT" , c);
	
	puts(c);
	return 0;
}

/*
 * Search and replace a string with another string , in a string
 * */
char *str_replace(char *search , char *replace , char *subject_orig)
{
	char *subject , *buffer = NULL , *p;
	int size;
	subject = strdup(subject_orig);
	
	while( (p = strstr(subject, search)) )
	{
		size = strlen(subject) + 1 + strlen(replace) - strlen(search);
		buffer = (char*) realloc(buffer , size );
		
		if(buffer == NULL)
		{
			printf("realloc failed");
			exit(0);
		}
		
		//Copy characters from 'subject' start to 'search' string
		strncpy(buffer, subject , p - subject );
		buffer[p-subject] = '\0';

		sprintf( buffer + (p - subject) , "%s%s" , replace, p + strlen(search));
		
		//Save the new buffer in the subject
		subject = (char*) realloc( subject , strlen(buffer) );
		strcpy(subject , buffer);
	}
	
	free(buffer);
	
	return subject;
}


###########Output


REPLACEMENTgoogle.com.REPLACEMENTabcd.com.REPLACEMENTsadasdasd.REPLACEMENT