Leap Year Basic C++ Boolean始终返回true

Question

我写了这段代码来确定输入的年份是否是闰年.意思是,那些被4和400整除的是闰年,而100或其他东西则不是.

但是,我的程序总是为布尔值返回true,因此输出将相信每年都是闰年.

到目前为止,这是我的代码:

#include <iostream>
#include <cmath>
#include <string>
#include <iomanip>

using namespace std;
 bool leap_year(int year);
int main()
{
    int year; 
     bool leap_year(int year);
    cout << "Please input the year in question: ";
    cin >> year;
    if (leap_year == false)
    {
        cout << "The year is not a leap year.  ";
    }
    else
    {
        cout << "The year is a leap year. ";
    }
    return 0;
}
  bool leap_year(int year)
{

    if (year % 4 == 0)
    {
        bool leap_year = true;
    }
    else if (year % 400 == 0)
    {
        bool leap_year = true;
    }
    else if (year % 100 == 0)
    {
        bool leap_year = false;
    }
    else
    {
        bool leap_year = false;
    }

    if (bool leap_year = false)
    {
        return false;
    }
    else
    {
        return true;
    }
}

Answer 1

你正在声明一堆局部变量

else if (year % 100 == 0)
{
    bool leap_year = false;
}

只要}括号,此变量超出范围,您存储的值也是如此.

if (bool leap_year = false)
{
    return false;
}

这是定义变量leap_year并将其赋值为false.if反过来将评估false,因此它总是会转到其他条件.

我冒昧地重写了一部分程序.您现在可以看到如何对函数进行调用.同样在函数中,局部变量is_leap_year用于存储返回值,最后返回.我也纠正了逻辑,因为之前的第一个%4检查是正确的,并且没有其他if语句将被执行,这不是你想要的.

#include <iostream>
#include <cmath>
#include <string>
#include <iomanip>

using namespace std;
bool leap_year(int year);
int main()
{
    int year; 
    cout << "Please input the year in question: ";
    cin >> year;
    if (leap_year(year) == false)  //Call the function and check if return is false
    {
        cout << "The year is not a leap year.  ";
    }
    else
    {
        cout << "The year is a leap year. ";
    }
    return 0;
}
  bool leap_year(int year)
{
    bool is_leap_year = false;
    if (year % 4 == 0)
    {
       is_leap_year = true;
    }
    if (year % 100 == 0)
    {
        is_leap_year = false;
    }
    if (year % 400 == 0)
    {
        is_leap_year = true;
    }
    return is_leap_year;
}