C++ fmax() and fmin()用法及代碼示例

在cmath頭文件中定義了fmax()和fmin()函數。

1. fmax()函數：該函數的語法為：

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

   該函數的輸入是float，double或long double類型的兩個值。該函數返回兩個輸入值中的最大值。

   下麵是示例C++程序，顯示fmax()函數的工作：

   
   

   // 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; 
   }

   輸出：

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

2. fmin()函數：該函數的語法為：

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

   該函數的輸入是float，double或long double類型的兩個值。該函數返回兩個輸入值中的最小值。

   下麵是示例C++程序，顯示fmin()函數的工作：

   // 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; 
   }

   輸出：

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

注意：考慮一下函數的參數為​​不同類型的情況。在這種情況下，參數首先由函數隱式類型轉換，然後返回所需的最大值/最小值。
下麵是說明這種情況的示例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; 
}

輸出：

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