C++ iomanip setprecision()用法及代码示例

C++中iomaip库的setprecision()方法用于根据为此方法的参数指定的精度来设置ios库浮点精度。

setprecision(int n)

参数：此方法接受n作为参数，该参数是要设置浮点精度的整数参数。返回值：此方法不返回任何内容。它仅用作流操纵器。示例1：

C++

// C++ code to demonstrate 
// the working of setprecision() function 
  
#include <iomanip> 
#include <ios> 
#include <iostream> 
  
using namespace std; 
  
int main() 
{ 
  
    // Initializing the decimal 
    double num = 3.142857142857; 
  
    cout << "Before setting the precision:\n"
         << num << endl; 
  
    // Using setprecision() 
    cout << "Setting the precision using"
         << " setprecision to 5:\n"
         << setprecision(5); 
  
    cout << num << endl; 
  
    // Using setprecision() 
    cout << "Setting the precision using
            "<<" setprecision to 9:\n " 
         << setprecision(9); 
  
    cout << num << endl; 
  
    return 0; 
}

输出：

Before setting the precision:
3.14286
Setting the precision using setprecision to 5:
3.1429
Setting the precision using setprecision to 9:
3.14285714

范例2：

C++

// C++ code to demonstrate 
// the working of setprecision() function 
  
#include <iomanip> 
#include <ios> 
#include <iostream> 
  
using namespace std; 
  
int main() 
{ 
  
    // Initializing the decimal 
    double num = 3.14; 
  
    cout << fixed; 
  
    cout << "Before setting the precision:\n"
         << num << endl; 
  
    // Using setprecision() 
    cout << "Setting the precision using"
         << " setprecision to 5:\n"
         << setprecision(5); 
  
    cout << num << endl; 
  
    // Using setprecision() 
    cout << "Setting the precision using"
         << " setprecision to 9:\n"
         << setprecision(9); 
  
    cout << num << endl; 
    return 0; 
}

输出：

Before setting the precision:
3.140000
Setting the precision using setprecision to 5:
3.14000
Setting the precision using setprecision to 9:
3.140000000

参考： http://www.cplusplus.com/reference/iomanip/setprecision/

相关用法

注：本文由纯净天空筛选整理自guptayashgupta53大神的英文原创作品 iomanip setprecision() function in C++ with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。