如何使用setw和setfill多次重置cout中的格式化功能

Question

How can I use io manipulators like setfill and setw repeatedly without wrecking the output that happens below the other what I'm asking is I want to create a text based window not using win32 functions but a made version in command prompt I'm trying to use IO manipulators to create the shape of the window using a character I have selected in my program but what happens is

cout  <<setfill(width) << setfill(style)

want to fill the top with x's and the leave the bottom alone and setfill the bottom of the title bar variable

cout  <<endl<< titleBar << setw(width) << "[_][]][x]" << endl;

---

#include <iostream>
#include <iomanip>
using namespace std; 


class window
{
    public:
    window(const char * title)
    {
        windowTitle = title;
    }

    void createWindow(int width,int height,char windowStyle,const char * titleBar,const char * windowClass)
    {
        char style = windowStyle;
        cout <<setw(width) <<setfill(style) <<setw(0) <<endl;
        cout << titleBar << setw(width) << "[_][]][x]" <<endl;
        cout <<setw(width) <<setfill(style) <<setw(0) <<endl;
    }

    const char * getTitle() const { return windowTitle; }                 
    private:
    const char * windowTitle;
    const char * windowClass;

};

int main ()
{
    window myWindow("Windows Programming");
    myWindow.createWindow(50,100,'x',myWindow.getTitle(),"windowclass");

    system("pause");

    return 0;
}

Answer 1

I can't say I fully comprehend the question, but resetting the fill and width could be done as shown:

void createWindow(int width,int height,char windowStyle,const char * titleBar,const char * windowClass)
{
    char style = windowStyle;

    char prev_char = cout.fill(style);

    cout << setw(width) << "" << endl;

    cout.fill(prev_char);

    cout << titleBar << setw(width - strlen(titleBar)) << "[_][]][x]" <<endl;

    cout << setw(width) << setfill(style) << "" << endl;
}

The main idea is to use the corresponding member functions from cout which return the previous value which you can later use to reset the fill/width. Running this code would yield the following result:

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Windows Programming                      [_][]][x]
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Update:

I have updated the code so I can give you a better explanation.

the functions setw and setfill basically modify some of the internal flags/variables of the std::ostream. setfill permanently modifies the fill character, but setw only modifies the width for the next element. So let's analyse the code.

Instead of using setfill, I am calling directly the method from the std::ostream to set the fill value. The main reason I do this is because it returns the previous value it contained so I can restore later:

char prev_char = cout.fill(style);

The next step is to print the "title bar" or however you wan't to call it. To do so I set the width with setw to the parameter provided. As I said before the width is only applied to the next printed element, hence the width characters of value style are printed before the empty string:

cout << setw(width) << "" << endl;

In the next line we just recover the original fill value, which is very likely just a space:

cout.fill(prev_char);

Then we print the titlebar and the buttons, but we apply a new width so that we can fill the space between the titlebar text and the buttons with white spaces:

cout << titleBar  << setw(width - strlen(titleBar)) << "[_][]][x]" <<endl;

Finally, we print another line of x's of size width , but since we already have the original fill character stored in a variable, we can directly use the setfill function:

cout << setw(width) << setfill(style) << "" << endl;