C++中的fMax（）和Fmin（）

fmax（）和fmin（）函数在中定义 数学库 头文件。

1. fmax（）函数： 此函数的语法为：

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

   该函数的输入是两个float类型的值，double或long double。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 << "" ; // Find maximum value when inputs have // opposite sign. val = fmax(-10.0, 1.0); cout << fixed << setprecision(4) << "fmax(-10.0, 1.0) = " << val << "" ; // 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 << "" ; 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： 此函数的语法为：

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

   该函数的输入是两个float类型的值，double或long double。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 << "" ; // Find minimum value when inputs have // opposite sign. val = fmin(-10.0, 1.0); cout << fixed << setprecision(4) << "fmin(-10.0, 1.0) = " << val << "" ; // 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 << "" ; 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： 考虑函数的参数是不同类型的情况。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。 下面是示例C++程序，说明了这种情况：

   // 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 << "" ; // 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 << "" ; return 0; }

   输出：

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