C + + flow operator

C language used to know the accuracy of C-format control is very simple and easy, just learn C + + may not know how to use these features in C + +. Here are two ways to use these features.

Variable use:

    int64;    double123.45;    double0.0183;

I. Using flow manipulation operators
First you have to include the header file
1. Width control

    cout‘#‘ << endl;    //宽度控制不会影响下一个变量    cout << setw(10‘#‘ << endl;//默认右对齐    cout‘#‘ << endl;

2. Alignment control

    //对齐控制会影响下面的变量对其方式    cout << setw(10‘#‘ << endl;//左对齐    cout << setw(10‘#‘ << endl;    cout << setw(10‘#‘ << endl;//还原成右对齐    //cout << setw(10) << resetiosflags(ios::left) << n << ‘#‘ << endl << endl;//还原成右对齐

3. Fill control

    //填充控制会影响下面的输出    cout << setw(10) << setfill(‘@‘‘#‘ << endl;    cout << setw(10‘#‘ << endl;    cout << setw(10) << setfill(‘ ‘‘#‘//还原成空格填充

4. Precision Control

    //精度控制会影响下面的输出    cout << setprecision(4//控制有效数字的位数    cout << setprecision(2) << d2 << endl;//四舍五入，而不是简单的截断    cout << d << endl;    cout << setiosflags(ios::fixed);      //控制小数点后面的位数    cout << setprecision(4//同样是四舍五入    cout << setprecision(2) << d2 << endl;

5. Control of the input system

    cout<<"Dec:"<< n << Endl;cout<<"Oct:"&LT;&LT;OCT << n << Endl;cout<<"Hex:"<< hex << n << endl;cout<< n << Endl;cout<< setiosflags (ios::showbase);//Display the symbol in front of the corresponding system    cout<<"Dec:"<< Dec <<n << Endl;cout<<"Oct:"<< Oct << n << Endl;cout<<"Hex:"<< hex << n << endl;cout<< SetBase (8) << n << Endl;//Binary output    cout<< SetBase (Ten) << n << Endl;cout<< SetBase ( -) << n << Endl;

Two. In the way of stream member functions (without Iomanip header file)
1. Width control

    cout << n << endl;    cout.width(10);    cout‘#‘ << endl;

2. Alignment control

    cout << n << endl;    cout.width(10);    cout.setf(ios::left);    cout‘#‘ << endl;//  cout.width(10);//  cout.setf(ios::right);//  cout << n << ‘#‘ << endl;    cout.width(10);    cout.unsetf(ios::left);    cout‘#‘ << endl;

3. Fill control

    cout << n <<‘#‘<< endl;    cout.width(10);    cout.fill(‘@‘);    cout‘#‘ << endl;    cout.width(10);    cout‘#‘ << endl;    cout.width(10);    cout.fill(‘ ‘);    cout‘#‘ << endl;

4. Precision Control

    cout.precision(2);   //这个会影响下面的输出    cout << d << endl;    cout << d2 << endl;    cout.setf(ios::fixed);  //控制小数点位数    cout << d << endl;    cout << d2 << endl;

5. Control of the input system

    cout//要切换进制的时候需要先去掉原先的进制    cout.setf(ios::oct);    cout << n << endl;

The output is 100.

C + + flow operator