c - 我的主 while 循环将运行，并在用户输入 'y' 或 'n' 时再次运行。不管用户怎么说

Question

当我添加主 while 循环时，程序总是运行，然后再次运行并显示一条消息告诉我存在无效数据(来 self 的第一次输入验证)。谁能告诉我如何让用户选择结束程序？基本上，我只想让用户可以选择按“y”或“n”来结束程序。愿意听取新想法，例如使用 for 或 do while 循环!我只想让程序通过。我希望用户能够通过任意多次，同时可以选择在每次通过后离开。

#include <stdio.h>

//Declare functions
void displayWelcome(void);
double getAverage(double yards, double carries);
void endMessage(void);


int main()
{
//Declare variables
    double yards, carries, average, bestAverage;
    char again = 'y';
//Call function to display welcome message
    displayWelcome();

    while (again == 'y' || again =='Y') {
//Prompt user for the number of yards,
    printf("Enter the number of yards:");
/*
Scan in the value of 'yards' and send user into a loop if they enter 
incorrect data
While loop to validate the data of the value 'yards'
*Works with a numerical value greater than 0
*/
    while ( 1 != scanf( "%lf", &yards ) || yards <= 0)
{

    fflush(stdin);
    printf("Enter a numerical value greater than zero:");
}
//Prompt user for the number of carries, followed by an input scan to get 
//value of carries
    printf("Enter the number of carries:");
/*
Scan in the value of 'yards' and send user into a loop if they enter 
incorrect data
    While loop to validate the data of the value 'carries'
*Works with a numerical value greater than zero
*/
    while ( 1 != scanf("%lf", & carries) || carries <= 0)
{
//Refreshes the input value of the variable 'carries' and prompts the 
//user to type in new value for 'carries'
    fflush(stdin);
    printf("Enter a numerical value greater than zero:");
}

    average = getAverage( yards, carries);
    printf("yards:%g carries:%g average:%g\n", yards, carries, average);
//Give the user the option to run the program again
   printf("Would you like to run the program again? Enter (y)es or (n)o\n");
   scanf("%c\n", &again);
}
   endMessage();
   return 0;
}

    void displayWelcome(void)
{
    printf("Welcome to Football Stats\n");
}

    double getAverage(double yards, double carries)
{
    double average;
    average = yards + carries / 2;
    return average;
}
    void endMessage(void){
    printf("\nThese results were brought to you by ");
}

更新(问题仍未回答) 当我按“n”停止程序时它起作用了。但是，当我按“y”再次运行它(使用新输入的代码)时，它也会停止程序。回到我的问题，任何人都可以看到我做错了什么，以便我可以让用户选择关闭程序吗？

最终更新 我发现了这个问题。我做了 "scanf("%c\n", &again);"(清除值)当我应该放置“scanf(”\n%c“，&again)；”。感谢所有花时间帮助我的人!

Answer 1

while (again == 'y' || 'Y') { ...

|| 不是那样工作的。 &&和||用于连接完整的 bool 表达式。你的意思是:

while (again == 'y' || again == 'Y') { ...

在 C 中，表达式 'Y' 只是整数 89，C 将其解释为“真”，因为它不是零。因此，您的第一个表达式是

while (<something> || <true>) { ...

这总是正确的。