#include <bits/stdc++.h>

using namespace std;

#define N 6

void identifying_Code (char str[],int n)
{
    int i,j,len;
    char pstr[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJLMNOPQRSTUVWXYZ";
    len = strlen(pstr);
    srand(time(NULL));
    for (i = 0; i < n; i++)
    {
        j = rand()%len;      //生成0~len-1的随机数
        str[i] = pstr[j];
    }
    str[i] = '\0';
}

int main()
{
    int n = 3;
    int flag = 0;
    char code[7],str[7];
    while (n)
    {
        identifying_Code (code,N);
        cout<<"请输入验证码:"<<code<<"   (你还有"<<n<<"次机会)"<<endl;
        scanf("%s",str);
        n--;
        if(strcasecmp(code,str) == 0)              //不区分大小写
        {
            n = 0;
            flag = 1;
            cout<<"验证正确."<<endl;
        }
    }
    if (flag == 0)
        cout<<"验证失败."<<endl;
    return 0;
}