我希望我的代碼重復 3 次，但循環沒有結束。 有誰知道我該如何解決這個問題？

Question

這是代碼：

    #include <stdio.h>
    #include <string.h>
    #include <conio.h>
    #include <iostream>
    #define repeat(n)
    #define endrepeat

    int main()
    {
    int login;
    
    char Username [4];
    char Password [4];
 
    printf("\t\tPlease enter your user name: ");
    scanf("%s", Username);
    printf("\t\tPlease enter your user password: ");
    scanf("%s", Password);

    if (strcmp (Username,"Jane")==0 && strcmp(Password,"1234")==0 || 
    strcmp(Username,"Arin")==0 && strcmp (Password,"3201")==0 || strcmp 
    (Username,"Jake")==0 && strcmp (Password,"4312")==0 || strcmp 
    (Username,"Jazz")==0 && strcmp (Password,"4456")==0)
    {
    printf("ACCESS GRANTED");

    system("CLS");
    getch();
    }
    
    else
    {
    printf("INVALID USERNAME OR PASSWORD ENTERED.\n");
    printf("\t\tPlease enter your user name: ");
    scanf("%s", Username);
    printf("\t\tPlease enter your user password: ");
    scanf("%s", Password);
    }
    int repeat;
    repeat = 0;
    do  {
    printf("INVALID USERNAME OR PASSWORD ENTERED.\n");          
    printf("\t\tPlease enter your Username: ");
    scanf("%s", Username);
    printf("\t\tPlease enter your password: ");
    scanf("%s", Password);
    repeat + 1 ;
    } while(repeat<3);
    endrepeat;
    
    return 0;
    }

我希望代碼在退出之前重復 3 次。 當我嘗試運行代碼時，它會不斷重復。 我是編碼新手，很抱歉，如果它很容易解決。 :) 我嘗試過使用不同的重復方法，但我仍然遇到同樣的問題。

Answer 1

像這樣增加repeat變量：

repeat = repeat + 1;

或者

repeat += 1;

或者

repeat++;

在if語句中使用括號來分隔邏輯並避免得到錯誤的結果，如下所示：

if ((strcmp(Username,"Jane") == 0 && strcmp(Password,"1234") == 0) || 
(strcmp(Username,"Arin") == 0 && strcmp(Password,"3201") == 0) || 
(strcmp(Username,"Jake") == 0 && strcmp(Password,"4312") == 0) || 
(strcmp(Username,"Jazz") == 0 && strcmp(Password,"4456") == 0))
{

擺脫else語句，只需使用帶有if語句的do-while循環。 或者更好的是，您可以制作一個單獨的 function 來接收和驗證輸入。 這將使一切更具可讀性。

就像是：

bool requestInput()
{
   printf("\t\tPlease enter your Username: ");
   scanf("%s", Username);
   printf("\t\tPlease enter your password: ");
   scanf("%s", Password);

   if ((strcmp(Username,"Jane") == 0 && strcmp(Password,"1234") == 0) || 
       (strcmp(Username,"Arin") == 0 && strcmp(Password,"3201") == 0) || 
       (strcmp(Username,"Jake") == 0 && strcmp(Password,"4312") == 0) || 
       (strcmp(Username,"Jazz") == 0 && strcmp(Password,"4456") == 0))
   {
       return true;
   }

   printf("INVALID USERNAME OR PASSWORD ENTERED.\n");
   return false;
}


int main()
{
   bool accessGranted;
   int repeat = 0;

    do {
        accessGranted = requestInput();
        repeat++;
    } while(repeat<3 && !accessGranted);

    if(accessGranted)
    {
       printf("ACCESS GRANTED");
       // ...
    }
}

Answer 2

將 1 添加到repeat變量后，您必須保存結果，例如，如下所示：

repeat = repeat + 1

較短的替代方案是

repeat += 1

或者

repeat++

一般來說，在這種情況下，我會使用 for 循環。