控制作浮点数目

[root@localhost cpp]# cat cout_setprecision.cpp
#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    float  val=1.2345;
    cout <<"0: "<< setprecision(0)<<val<<endl;
    cout <<"1: "<< setprecision(1)<<val<<endl;
    cout <<"2: "<< setprecision(2)<<val<<endl;
    cout <<"3: "<< setprecision(3)<<val<<endl;
    cout <<"4: "<< setprecision(4)<<val<<endl;
    cout <<"5: "<< setprecision(5)<<val<<endl;
    cout <<"6: "<< setprecision(6)<<val<<endl;
    return 0;
}


[root@localhost cpp]# ./cout_setprecision
0: 1
1: 1
2: 1.2
3: 1.23
4: 1.235
5: 1.2345
6: 1.2345