c 查找替换字符串

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

char *mystrstr(char *s1, char *s2)
{
	int i;
	if (*s2)
	{
		while(*s1)
		{
			for(i = 0; *(s1+i) == *(s2+i); i++)
			{
				if(!*(s2+i+1))
					return (char *)s1;
			}
			s1++;
		}
		return NULL;
	}
	else  
    {  
        return (char*)s1;  
    } 
}

void fun(char *str, char *temp,char *substr1, char *substr2)
{

	int len,len1,len2;
	len1 = strlen(substr1);
	len2 = strlen(substr2);
	char *p_str = str;
	//字符串中第一次出现替换串的位置,并返回指针(找不到则返回null).
	char *p = mystrstr(str, substr1);
	if(p)
	{
		while(p)
		{
			//被替换串前边字符串的长度.
			len = (int)(p - p_str);
			//复制到输出字符串.
			memcpy(temp, p_str, len);
			memcpy(temp+len, substr2 , len2);
			//跳过被替换串.
			p_str = p + len1;
			//移动到最后
			temp = temp + len + len2;
			//重新查找
			p = strstr(p_str, substr1);
		}
		//拷贝剩余
		strcpy(temp, p_str);
	}
	else
	{
		strcpy(temp, p_str);
	}
}

int main(int argc, char *argv[])
{
	printf("Hello, world\n");

	char str[][30] = {"abcedfrbcxybc","abcedfrbceybce"};
	char sub1[][10] = {"bc", "bce"};
	char sub2[][10] = {"ghi", "gh"};
	char temp[30] = "";
	int i;

	for(i = 0; i < 2; i++)
	{
		memset(temp,0,30);
		printf("str--->%s\n",str[i]);
		printf("sub1--->%s\n",sub1[i]);
		printf("sub2--->%s\n",sub2[i]);
		fun(str[i], temp, sub1[i], sub2[i]);
		printf("%s, len:%d\n",temp, strlen(temp));
	}	

	return 0;
}