gistfile1.c

/*
 * Search and replace a string with another string , in a string
 * */
char *str_replace(char *search , char *replace , char *subject)
{
	char *new_subject = NULL , *p , *temp;
	int size;
	
	//subject to work upon
	new_subject = strdup(subject);
	
	//temp needs to be max as big as original subject , it will always hold a part of unconverted string
	temp = malloc(strlen(subject));
	
	while( (p = strstr( new_subject , search)) )
	{
		size = strlen(new_subject) + 1 + strlen(replace) - strlen(search);
		new_subject = (char*) realloc(new_subject , size );
		
		//Copy forward string to temp;
		sprintf(temp , "%s" , p + strlen(search));
		
		//write replacement to subject
		strcpy(p , replace);
		
		//write back temp string
		sprintf( p+strlen(replace) , "%s" , temp);
	}
	
	return new_subject;
}