1021 字符替换

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

#define MAX 256


int str_replace(char *str, size_t n,
                const char *old,
                const char *new);

char a[MAX], b[MAX], c[MAX];

int main()
{
	while(scanf("%s%s%s", a, b, c) == 3)
	{
        str_replace(a, strlen(a), b, c);
    	printf("%s\n", a);
	}
	return 0;
}

int str_replace(char *str, size_t n,
                const char *old,
                const char *new)
{
    size_t old_len = strlen(old);
    size_t new_len = strlen(new);

    while ((str = strstr(str, old)) != NULL)
    {
          size_t len = strlen(str);

          memmove(str + new_len, str + old_len, len+1);

          memcpy(str, new, new_len);

          str += new_len;
    }
    return 0;
}