cout.width

[tikoti]

Hi all!

I have a little problem here, I would like the width function in cout applied to all the sucesive outputs. However, it is only applied to the next output only, I mean, with this code I get

0:00:10:20:30:4
1:01:11:21:31:4
2:02:12:22:32:4
3:03:13:23:33:4
4:04:14:24:34:4
5:05:15:25:35:4
6:06:16:26:36:4
7:07:17:27:37:4
8:08:18:28:38:4
9:09:19:29:39:4

and I would like
0:0 0:1 0:2 0:3 0:4
1:0 1:1 1:2 1:3 1:4
2:0 2:1 2:2 2:3 2:4
3:0 3:1 3:2 3:3 3:4
4:0 4:1 4:2 4:3 4:4
5:0 5:1 5:2 5:3 5:4
6:0 6:1 6:2 6:3 6:4
7:0 7:1 7:2 7:3 7:4
8:0 8:1 8:2 8:3 8:4
9:0 9:1 9:2 9:3 9:4

#include <iostream>

using namespace std;

int main(void)
{
  cout.width(8);
  cout.setf(std::ios::fixed | std::ios::right);
  for (int row = 0; row < 10; ++row) {
    for (int column = 0; column < 5; ++column) {
      cout << row << ":" << column;
    }
    cout << endl;
  }
  return 0;
}

I realize that by moving the cout.width inside the loop but do the trick in this example, but not in one without a loop resulting in having to specify the width in every output.

My question is, is there a way in which the width function applies to everything that goes after it?

Thank you in advance!

[pseudorandom21]

Stream manipulator "setw" in <iomanip>

[m4ster_r0shi]

The setw manipulator has the same problem. It only affects the next output operation.
AFAIK,   there  is  no  way  you  can  avoid   setting   the   width  over  and  over   again.
Maybe   someone   else   knows   better   though.   Here's  a  simple   hackish   solution:

#include <iostream>
#include <sstream>

using namespace std;

class ostream_w : public ostream
{
    unsigned w;

public:

    ostream_w(ostream & os_, unsigned w_): w(w_)
    {
        rdbuf(os_.rdbuf());
    }

    template <class T>
    ostream_w & operator << (const T & t)
    {
        width(w);

        static_cast<ostream &>(*this) << t;

        return *this;
    }

    // necessary for endl
    ostream_w & operator << (ostream & (*pf)(ostream &))
    {
        pf(static_cast<ostream &>(*this));

        return *this;
    }
};

int main()
{
    ostream_w cout_w6(cout, 6);

    cout_w6.setf(ios::right);

    for (int row = 0; row <= 12; ++row)
    {
        for (int column = 0; column <= 10; ++column)
        {
            stringstream buffer;

            buffer << row << ":" << column;

            cout_w6 << buffer.str();
        }

        cout_w6 << endl;
    }

    return 0;
}

[tikoti]

Stream manipulator "setw" in <iomanip>

Unfortunatelly it has the same behaviour, it only applies to the following output

any idea?

[L7Sqr]

If I modify your code to use an object to do the output instead of putting the code inline you still have to call the manipulator functions but they happen every time. Consider

struct Formatter {
    void operator()(int r, int c) {
        std::cout.width(8);
        std::cout.setf(std::ios::fixed | std::ios::right);
        std::cout << r << ':' << c;
    }
};

int main(void)
{
  Formatter format;
  for (int row = 0; row < 10; ++row) {
    for (int column = 0; column < 5; ++column) {
        format(row,column);
    }
    std::cout << std::endl;
  }
  return 0;
}

[tikoti]

I see...

I think I will have to use one of those workarounds you have propossed

I always learn when I ask things here!

Thank you for all your answers!