📜  带有示例的C++中的iomanip setprecision()函数

📅  最后修改于: 2021-05-30 18:17:45             🧑  作者: Mango

C++中iomaip库的setprecision()方法用于根据指定为该方法参数的精度来设置ios库浮点精度。
句法:

setprecision(int n)

参数:此方法接受n作为参数,它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。它仅充当流操纵器。
范例1:

C++
// C++ code to demonstrate
// the working of setprecision() function
  
#include 
#include 
#include 
  
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;
}


C++
// C++ code to demonstrate
// the working of setprecision() function
  
#include 
#include 
#include 
  
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: 
3.14286
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 
#include 
#include 
  
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/

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