<验证码的产生>C语言---验证码的产生和验证

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#define N 5

void identifying_Code (char str[],int n) {
    int i,j,len;
    char pstr[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJLMNOPQRSTUVWXYZ";
    len = strlen(pstr);         //求字符串pstr的长度
    srand(time(0));
    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[N+1],str[N+1];
    while (n) {
        identifying_Code (code,N);
        printf("请输入验证码<您还剩%d机会>:%s\n",n,code);
        scanf("%s",str);
        n--;
        if(strcmp(code,str) == 0) {            //区分大小写的验证码
            n = 0;
            flag = 1;
            printf("验证正确.\n");
        }
    }
    if (flag == 0)
        printf("对不起，您的账号已锁定.\n");
    return 0;    
}