字符串长度拷贝连接

#include <stdio.h>/**模拟C语言系统提供的strlen、strcat、strcpy**//*力求代码简洁，易懂，尽量和系统提供函数类似*//*字符串长度*/int mystrlen(const char *str){    const char *s = str;        if(NULL == str)            return -1;                while(*s != '\0') s++;        return (s - str);}/*字符串拷贝*/char *mystrcpy(char *dst, const char *src){     char *s = dst;          while(*src) *dst++ = *src++;     *dst = '\0';          return s;}/*连接*/char *mystrcat(char *dst, const char *src){     char *s = dst;          dst += mystrlen(dst);     mystrcpy(dst,src);          return s;}int main(){    char str[200]="adbcde";    char *s="ddfsdfsdfdsfdsf";    //这个地方大家根据函数特点自己DIY一下     puts(mystrcat(str,s));    system("pause");    return 0;}