C 程序输出有问题

Question

据我所知，不管任何其他问题，下面的程序都应该打印出标题和菜单选项，然后提示用户输入。

但是，它什么都不做，当我停止执行时，它会打印出菜单等，然后，由于它没有要求用户输入选项，它会重复打印 "This is not a valid option" 行。

*编辑：我已经完全删除了循环。我在程序中所拥有的只是打印标题、打印菜单、要求用户输入，在我终止之前，我仍然无法在控制台上看到任何东西。我的输入请求有问题吗？

EDIT2：绝对是 scanf，因为没有它一切正常。我运行带有附加功能的代码可以打印出存储在选项中的值，当我在要求用户输入之前没有将它设置为 0 时它告诉我 -1。该程序似乎是自动分配选项，而不是费心询问用户他们想要什么。

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

int main ()
{
    /*Print Title*/
    printf("Maths Quiz Game \n"); 
    printf("\n");

    int i;
    int rightCount = 0; //count of right answers
    int wrongCount = 0; //count of wrong answers
    int questions = 0; //user input for number of questions
    int exit = 0; //store exit option
    int option = 0; //menu option

    while(exit == 0) //while loop that keeps program running until exit is chosen
    {
        /*Menu Options*/
        printf("Please choose an option from the menu below. Enter the number of your choice. \n");
        printf(" 1. Choose number of questions for this round. (Max = 5) \n");
        printf(" 2. Start Quiz \n");
        printf(" 3. Display total of right and wrong answers. (Only availanle after quiz) \n");
        printf(" 4. Exit Game \n");

        scanf("%d", &option); //taking user menu option

        /*Error check for any input that is not a valid option. It continues until valid entry*/
        while((option != 1) || (option != 2) || (option != 3) || (option != 4))
        {
            printf("\n That is not a valid option. Please try again. \n");
            scanf("%d", &option);
        }

Answer 1

while((option != 1) || (option != 2) || (option != 3) || (option != 4))

你输入的任何选项值都假设 1，while() 的第一个条件为假但其余为真所以进入循环并打印 "That is not a valid option. Please try again." 所以 替换 ||使用逻辑 And(&&).

while((option != 1) && (option != 2) && (option != 3) && (option != 4))

现在这里如果你输入正确的输入它不会显示"That is not a valid option. Please try again"

Answer 2

改一下怎么样

while((option != 1) || (option != 2) || (option != 3) || (option != 4))
{
    printf("\n That is not a valid option. Please try again. \n");
    scanf("%d", &option);
}

到其他东西，比如

if ((option != 1) || (option != 2) || (option != 3) || (option != 4))
{
    printf("\n That is not a valid option. Please try again. \n");
    // scanf("%d", &option);  // This is probably not required
}

或

if ( option >= 1 && option <= 4)
{
    printf("\n That is not a valid option. Please try again. \n");
    // scanf("%d", &option);
}

因为你在外面使用无限循环，为什么你需要一个内部？如果选择了不可用的选项，您只需选中该选项并显示菜单。

之后您可以将所有逻辑放入此 if 中，每个选项对应一个选择。

更好地使用switch以便更好地理解

/* After selecting an option */
switch (option)
{
    case 1:
         /* Do the operation according */
         break;

    case 2:
         /* Do the operation according */
         break;

    case 3:
         /* Do the operation according */
         break;

    case 4:
         /* Do the operation according */
         break;

    default:
         /* If none of the option selected */
         printf ("Wrong input! \n")
         break;
}

希望你明白了。

Answer 3

问题出在 printf 函数上，它在您输入以下选项后才打印出来，直到用户回答后才询问。 printf 解决后的简单刷新。

C 程序输出有问题

Having trouble with C program output

c

compiler-errors

output

borland-c