函数原型:
setprecision(streamsize _Prec);
功能:
使用setprecision(n)可控制输出流显示浮点数的数字个数。C++默认的流输出数值有效位是6
参数:
streamsize _Prec 浮点数的精度
返回值:
The manipulator returns an object that, when extracted from or inserted into the
stream str, calls str.precision(_Prec), and then returns str.
要求:
Header: <iomanip>
Namespace: std
#include <iostream> #include <iomanip> //格式控制 using namespace std; int main() { double PI= 3.141592653; cout<<"when default PI= "<<PI<<endl; //(1) for(int i=0;i<13;i++) { cout<<"when setprecision("<<i<<") PI= "<<setprecision(i) <<PI<<endl; } } /********************** when default PI= 3.14159 when setprecision(0) PI= 3 when setprecision(1) PI= 3 when setprecision(2) PI= 3.1 when setprecision(3) PI= 3.14 when setprecision(4) PI= 3.142 when setprecision(5) PI= 3.1416 when setprecision(6) PI= 3.14159 when setprecision(7) PI= 3.141593 when setprecision(8) PI= 3.1415927 when setprecision(9) PI= 3.14159265 when setprecision(10) PI= 3.141592653 when setprecision(11) PI= 3.141592653 when setprecision(12) PI= 3.141592653 Process returned 0 (0x0) execution time : 0.062 s Press any key to continue. *********************/