c - C 中 Do-While 循环的问题

Question

我在编码方面非常新，我正在努力让这段代码循环(直到满足正确的标准.. 大写/小写字母和数字)我是否将 do while 循环放入正确的地方？？

非常感谢收到的任何帮助..

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#include <stdlib.h>

main()
{
    int i;
    int hasUpper, hasLower, hasDigit;
    char password[20];

    hasUpper = hasLower = hasDigit = 0; // initialising these three variables to false (o)

    printf("Please enter a alpha numeric password with upper and lower case\n");
    scanf(" %s", password);

    do {
        for (i = 0; i < strlen(password); i++) {
            if (isdigit(password[i])) {
                hasDigit = 1;
                continue;
            }

            if (isupper(password[i])) {
                hasUpper = 1;
                continue;
            }

            if (islower(password[i])) {
                hasLower = 1;
                continue;
            }
        }

        printf("Not so good, try again!");
        scanf(" %s", password);
    } while ((hasDigit) && (hasLower) && (hasUpper)==1);

    // This loop will only execute if all three variables are true

    if ((hasUpper) && (hasLower) && (hasDigit)) {
        printf("Great password!");
    }

    return 0;
}

Answer 1

您的 while 条件有问题，而且每次尝试后都需要清除变量，并且需要检查失败的打印输出。此外，将您的 scanf() 移到循环的开头会使事情变得更容易，并且无需在初始输入时在循环外添加额外的一个。

#include <stdio.h>
#include <string.h>
#include <stdbool.h>    // Use for boolean types

int main(int argc, const char argv[]) {    // Correct function signature
    int i = 0, plen = 0;
    bool hasUpper = false, hasLower = false, hasDigit = false;    //Change types to boolean
    char password[20] = {0};    // Initialise string with all '\0'

    printf("Please enter an alpha-numeric password with upper and lower case\n");

    do {
        hasUpper = false;    // Clear boolean variables for each new password
        hasLower = false;
        hasDigit = false;

        scanf("%s", password);
        password[19] = 0;    // ensure string is correctly terminated with '\0'
        plen = strlen(password); // Get the string length *once* per new password

        for (i = 0; i < plen; ++i) {
            if (isdigit(password[i])) {    // Use 'if...else' in place of 'continue'
                hasDigit = true;
            } 
            else if (isupper(password[i])) {
                hasUpper = true;
            }
            else if (islower(password[i])) {
                hasLower = true;
            }
        }

        if ((!hasDigit) || (!hasLower) || (!hasUpper)) {    // Check the booleans before printing fail message
            printf("Not so good, try again!");
            for (i = 0; i < 20; ++i) {
                password[i] = 0;    // Clear the string with all '\0'
            }
        }
    } while ((!hasDigit) || (!hasLower) || (!hasUpper));   // Correct the logic here

    printf("Great password!");   // Remove the unneeded boolean check here
    return 0;
}

我还会考虑用 if...else if 替换 if...continue 模式，因为使用 continue 是不好的练习。