字符串替换

//============================================================================
// Name : test.cpp
// Author : 
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
using namespace std;

extern "C"
{
#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

}

// You must free the result if result is non-NULL.
char *str_replace(char *orig, char *rep, char *with) {
char *result; // the return string
char *ins; // the next insert point
char *tmp; // varies
int len_rep; // length of rep
int len_with; // length of with
int len_front; // distance between rep and end of last rep
int count; // number of replacements

if (!orig)
return NULL;
if (!rep || !(len_rep = strlen(rep)))
return NULL;
if (!(ins = strstr(orig, rep)))
return NULL;
if (!with)
with = "";
len_with = strlen(with);

for (count = 0; tmp = strstr(ins, rep); ++count) {
ins = tmp + len_rep;
}

// first time through the loop, all the variable are set correctly
// from here on,
// tmp points to the end of the result string
// ins points to the next occurrence of rep in orig
// orig points to the remainder of orig after "end of rep"
tmp = result = (char *)malloc(strlen(orig) + (len_with - len_rep) * count + 1);

if (!result)
return NULL;

while (count--) {
ins = strstr(orig, rep);
len_front = ins - orig;
tmp = strncpy(tmp, orig, len_front) + len_front;
tmp = strcpy(tmp, with) + len_with;
orig += len_front + len_rep; // move to next "end of rep"
}
strcpy(tmp, orig);
return result;
}

int main() {
char *me = "thank you";
char *result = str_replace(me, "th", "me");
cout << result << endl; // prints !!!Hello World!!!
free(result);
return 0;
}