C++ isgreater()用法及代码示例

在C++中，isgreater()是用于数学计算的预定义函数。 math.h是各种数学函数所需的头文件。

isgreater()函数，用于检查赋予该函数的第一个参数是否大于赋予该函数的第二个参数。表示如果a是第一个参数，b是第二个参数，那么它将检查a> b是否。

用法:

bool isgreater(a, b)
参数：
a, b => These two are the parameters whose value we want to compare.
Result:
The function will return the true if a>b else it returns false.

Error: 
No error occurs with this function.
Exception: 
If a or b or both is NaN,
then the function raised an exception and return false(0).

// CPP code to illustrate 
// the exception of function 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    // Take any values 
    int a = 5; 
    double f1 = nan("1"); 
    bool result; 
  
    // Since f1 value is NaN so 
    // with any value of a, the function 
    // always return false(0) 
    result = isgreater(f1, a); 
    cout << f1 << " isgreater than " << a 
         << ":" << result; 
  
    return 0; 
}

输出：

nan isgreater than 5:0

例：

• 程序：

  // CPP code to illustrate 
  // the use of isgreater function 
  #include <bits/stdc++.h> 
  using namespace std; 
    
  int main() 
  { 
      // Take two any values 
      int a, b; 
      bool result; 
      a = 5; 
      b = 8; 
    
      // Since 'a' is not greater 
      // than 'b' so answer 
      // is false(0) 
      result = isgreater(a, b); 
      cout << a << " isgreater than " << b 
           << ":" << result << endl; 
    
      char x = 'd'; 
    
      // Since 'd' ascii value is greater 
      // than b vaiable so answer 
      // is true(1) 
      result = isgreater(x, b); 
      cout << x << " isgreater than " << b 
           << ":" << result; 
    
      return 0; 
  }

  输出：

  5 isgreater than 8:0
  d isgreater than 8:1
  

注意：使用此函数，您还可以将任何数据类型与任何其他数据类型进行比较。

应用

• 此函数可用于任何基于比较的排序算法。让我们在冒泡排序中使用它：

  // CPP code to illustrate the  
  // use of isgreaterequal function 
  #include <bits/stdc++.h> 
  using namespace std; 
    
  int main() 
  { 
      // taking inputs 
      int arr[] = { 5, 2, 8, 3, 4 }; 
      int n = sizeof(arr) / sizeof(arr[0]); 
    
      for (int i = 0; i < n - 1; i++)  
      { 
          for (int j = 0; j < n - i - 1; j++)  
          { 
              if (isgreater(arr[j], arr[j + 1]))  
              { 
                  int k = arr[j]; 
                  arr[j] = arr[j + 1]; 
                  arr[j + 1] = k; 
              } 
          } 
      } 
    
      cout << "Sorted array:"; 
      for (int i = 0; i < n; i++) { 
          cout << arr[i] << ", "; 
      } 
      return 0; 
  }

  输出：

  Sorted array:2, 3, 4, 5, 8,