C++ fmax() and fmin()用法及代码示例

在cmath头文件中定义了fmax()和fmin()函数。

1. fmax()函数：该函数的语法为：

   double fmax (double x, double y);
   float fmax (float x, float y);
   long double fmax (long double x, long double y);
   

   该函数的输入是float，double或long double类型的两个值。该函数返回两个输入值中的最大值。

   下面是示例C++程序，显示fmax()函数的工作：

   
   

   // CPP program to show working 
   // of fmax() function. 
     
   #include <cmath> 
   #include <iomanip> 
   #include <iostream> 
     
   using namespace std; 
     
   int main() 
   { 
       double val; 
     
       // Find maximum value when both the inputs 
       // are positive. 
       val = fmax(10.0, 1.0); 
       cout << fixed << setprecision(4) 
            << "fmax(10.0, 1.0) = " << val << "\n"; 
     
       // Find maximum value when inputs have 
       // opposite sign. 
       val = fmax(-10.0, 1.0); 
       cout << fixed << setprecision(4) 
            << "fmax(-10.0, 1.0) = " << val << "\n"; 
     
       // Find maximum value when both the inputs 
       // are negative. 
       val = fmax(-10.0, -1.0); 
       cout << fixed << setprecision(4) 
            << "fmax(-10.0, -1.0) = " << val << "\n"; 
     
       return 0; 
   }

   输出：

   fmax(10.0, 1.0) = 10.0000
   fmax(-10.0, 1.0) = 1.0000
   fmax(-10.0, -1.0) = -1.0000
   

2. fmin()函数：该函数的语法为：

   double fmin (double x, double y);
   float fmin (float x, float y);
   long double fmin (long double x, long double y);
   

   该函数的输入是float，double或long double类型的两个值。该函数返回两个输入值中的最小值。

   下面是示例C++程序，显示fmin()函数的工作：

   // CPP program to show working 
   // of fmin() function. 
     
   #include <cmath> 
   #include <iomanip> 
   #include <iostream> 
     
   using namespace std; 
     
   int main() 
   { 
       double val; 
     
       // Find minimum value when both the inputs 
       // are positive. 
       val = fmin(10.0, 1.0); 
       cout << fixed << setprecision(4) 
            << "fmin(10.0, 1.0) = " << val << "\n"; 
     
       // Find minimum value when inputs have 
       // opposite sign. 
       val = fmin(-10.0, 1.0); 
       cout << fixed << setprecision(4) 
            << "fmin(-10.0, 1.0) = " << val << "\n"; 
     
       // Find minimum value when both the inputs 
       // are negative. 
       val = fmin(-10.0, -1.0); 
       cout << fixed << setprecision(4) 
            << "fmin(-10.0, -1.0) = " << val << "\n"; 
     
       return 0; 
   }

   输出：

   fmin(10.0, 1.0) = 1.0000
   fmin(-10.0, 1.0) = -10.0000
   fmin(-10.0, -1.0) = -10.0000
   

注意：考虑一下函数的参数为​​不同类型的情况。在这种情况下，参数首先由函数隐式类型转换，然后返回所需的最大值/最小值。
下面是说明这种情况的示例C++程序：

// CPP program to show working 
// of fmin() and fmax()function 
// when input values are of 
// different data types. 
  
#include <cmath> 
#include <iomanip> 
#include <iostream> 
  
using namespace std; 
  
int main() 
{ 
    double val; 
  
    // Find minimum value when one of the inputs 
    // is of type float and other is of type 
    // double. 
    val = fmin(10.0f, 1.0); 
    cout << fixed << setprecision(4) 
         << "fmin(10.0f, 1.0) = " << val << "\n"; 
  
    // Find maximum value when one of the inputs 
    // is of type float and other is of type 
    // double. 
    val = fmax(10.0, -1.0f); 
    cout << fixed << setprecision(4) 
         << "fmax(10.0, -1.0f) = " << val << "\n"; 
  
    return 0; 
}

输出：

fmin(10.0f, 1.0) = 1.0000
fmax(10.0, -1.0f) = 10.0000