验证码校验

问题：随机生成一组验证码，输入并比较是否输入正确。

代码：

//定义验证字符
        char ver[] = {'0','1','2','3','4','5','6','7','8','9','q','w','e','r','t','y','u','i','o','p','a','s','d','f','g','h','j','k','l','z','x','c','v','b','m','n','Q','W','E','R','T','Y','U','I','O','P','A','S','D','F','G','H','J','K','L','Z','X','C','V','B','N','M'};
        //计算数组长度
        int length = sizeof(ver)/sizeof(char);
        //产生随机数下标
        Byte n1 = arc4random() % length;
        Byte n2 = arc4random() % length;
        Byte n3 = arc4random() % length;
        Byte n4 = arc4random() % length;
        //产生随机数
        char a = ver[n1];
        char b = ver[n2];
        char c = ver[n3];
        char d = ver[n4];
        printf("Verification code：%C %C %C %C\n",a,b,c,d);
        //定义输入验证码字符
        char num1[6];
        printf(" please input Verification code：\n");
        scanf("%s",num1);
        char A = num1[0];
        char B = num1[1];
        char C = num1[2];
        char D = num1[3];

<span style="white-space:pre">	</span>//使用while循环验证
        while(!( A== a & B == b & C == c & D == d)){
            printf("error，please input again：\n");
            scanf("%s",num1);
            A = num1[0];
            B = num1[1];
            C = num1[2];
            D = num1[3];
        }
        printf("input right\n");