求字符串长度
#include "stdafx.h"
#include<iostream>
using namespace std;
#define ERROR 1
int my_strlen(const char *p)
{
if (NULL == p)return ERROR;
const char *str = p;
for (; *p != '\0'; p++){}
return p - str;
//int num = 0;
//if (NULL == p)return ERROR;
//for (; p[num]; ++num);
//return num;
}
int main()
{
cout << "请输入一个字符串:";
int len;
char ch1[20] ;
cin >> ch1;
len = my_strlen(ch1);
switch (len)
{
case ERROR:cout << "输入字符串为NULL" << endl; break;
default:cout << "字符串长度为:" << len << endl; break;
}
return 0;
}