不用string库实现字符串替换

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

const char *kmp(const char *str, const char *substr)
{
    return strstr(str, substr); //kmp的实现略过
}

void str_replace(char *dest, const char *src, 
        const char *pattern, const char *replace)
{
    int lp = strlen(pattern), lr = strlen(replace);
    const char *temp = src, *last = src;
    while ((temp = kmp(temp, pattern)) != NULL)
    {
        //copy to dest
        memcpy(dest, last, temp - last);
        dest += temp - last;

        strcpy(dest, replace);
        dest += lr;

        temp += lp;
        last = temp;
    }
    strcpy(dest, last);
}

int main()
{
    char dest[1000];
    str_replace(dest, "abcdefgabcdefgabcdefg", "fg", "----");
    printf("%s\n", dest);

    str_replace(dest, "abcdefgabcdefgabcdefg", "ef", "----");
    printf("%s\n", dest);

    str_replace(dest, "hello world", "l", "ab");
    printf("%s\n", dest);
    return 0;
}