c - 为什么我的程序不会停止循环？

Question

我的任务是使用两种不同类型的循环(For、While、do While)。任务是要求用户输入1到10之间的数字，然后程序将从0开始计数到用户数。此外，如果用户输入 1 到 10 之外的数字，程序必须能够显示错误消息并要求用户再次输入数字。代码中包含错误消息并提示再次输入数字的部分工作得很好。但是，当我输入范围内的数字时，它要么不执行任何操作，要么从 0 到其数字无限次计数，并且不会停止循环计数。请帮忙!

#include <stdio.h>

int main(void)

{
    //Variables
    int num;
    int zero;

    //Explains to the user what the program will do
    printf("This program will count from 0 to a number you pick.\n\n");

    //Asks the user to input a value
    printf("Please enter a number (between 1 and 10): \n");
    scanf("%d", &num);


    //If the correct range was selected by the user
    while ( num >= 1 && num <= 10 )
    {
            for ( zero = 0; zero <= num; zero++ )
            {
                    printf("%d...", zero);

            }
    }

    //If a value outside of the accepted range is entered
    while ( num < 1 || num > 10)
    {
            printf("I'm sorry, that is incorrect.\n");
            printf("Please enter a number (between 1 and 10): \n");
            scanf("%d", &num);
    }


    printf("\n\n\n");

    return 0;


}

Answer 1

 while ( num >= 1 && num <= 10 )
    {
            for ( zero = 0; zero <= num; zero++ )
            {
                    printf("%d...", zero);

            }
    }

如果 num 介于 1 和 10 之间，则将永远运行，因为 num 在循环内不会更改 - 一旦进入，就永远处于循环中。

如果您输入“坏”值，那么您将跳过此步骤并进入第二个 while 循环。然而，一旦您通过输入“好”值退出 while 循环，剩下要执行的就是

printf("\n\n\n");

return 0;

您需要删除第一个 while 循环并将第二个循环移到 for 循环上方:

#include <stdio.h>

int main(void)

{
    //Variables
    int num;
    int zero;

    //Explains to the user what the program will do
    printf("This program will count from 0 to a number you pick.\n\n");

    //Asks the user to input a value
    printf("Please enter a number (between 1 and 10): \n");
    scanf("%d", &num);

    //If a value outside of the accepted range is entered
    while ( num < 1 || num > 10)
    {
            printf("I'm sorry, that is incorrect.\n");
            printf("Please enter a number (between 1 and 10): \n");
            scanf("%d", &num);
    }

   for ( zero = 0; zero <= num; zero++ )
   {
            printf("%d...", zero);

   }

    printf("\n\n\n");

    return 0;
}