From: Martin Ambuhl <mambuhl AT earthlink DOT net>
Newsgroups: alt.comp.lang.learn.c-c++,comp.os.msdos.djgpp
Subject: Re: boolalpha
Date: Wed, 26 May 1999 18:01:03 -0400
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To: djgpp AT delorie DOT com
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Chris Newton wrote:
> 
> David List wrote...
> >I see. Thanks, Ahn. Do you know of any other way to output 'true'
> >and 'false' instead of '1' and '0'?
> 
> Sorry, I'm not familiar with boolalpha.  What exactly are you trying to
> achieve here?  It's probably fairly simple to do in standard C++ by the
> sounds of things, but we need the details.
> 


Look at the following:

#include <iostream>
#include <iomanip>

// This relies on whether various macros are defined
// #define BOOLALPHA
// #define IOS_HAS_BOOLALPHA

// If your implementation supports a known (non-portable)
// constant for boolalpha functionality, change the following
// to reflect it and uncomment the line
// #define MAGIC_NUMBER 0200000


int main(void)
{
    bool x = false, y = true;
    cout << "This is a test of boolalpha"
#if defined(BOOLALPHA)
        << endl << "If the manipulator boolalpha works, the" << endl
        << " line should read \"x = false, y = true\"" << endl
        << "x = " << boolalpha << x << ", y = " << boolalpha << y
#endif
        << endl;
#if defined(IOS_HAS_BOOLALPHA)
    cout << "Even with a boolalpha manipulator, the following" << endl
        << "should work using the setiosflags(ios::boolapha) manipulator"
        << endl << "x = " << setiosflags(ios::boolalpha) << x
        << ", y = " << y << endl;
    cout << "Now we reset boolalpha " << resetiosflags(ios::boolalpha)
        << endl
        << "x = " <<  x << ", y = " << y << endl;
    cout << "Now trying cin.setf(ios::boolalpha)" << endl;
    cin.setf(ios::boolalpha);
    cout << "x = " << x << ", y = " << y << endl;
#endif
#if defined(MAGIC_NUMBER)
    cout << "A Magic number may solve the implementation's limitations" 
        << endl
        << "using setiosflags(MAGIC_NUMBER) manipulator"
        << endl << "x = " << setiosflags(MAGIC_NUMBER) << x
        << ", y = " << y << endl;
    cout << "Now we reset boolalpha " << resetiosflags(MAGIC_NUMBER)
        << endl
        << "x = " <<  x << ", y = " <<  y << endl;
    cout << "Now trying cin.setf(MAGIC_NUMBER)" << endl;
    cin.setf(MAGIC_NUMBER);
    cout << "x = " << x << ", y = " << y << endl;
#endif
    cout << "Finally, a simple solution" << endl;
    cout << "x = " << (x ? "true" : "false") << 
        ", y = " << (y ? "true" : "false") << endl;
}

/* vi: set cindent ts=4 sw=4 et tw=72: */


-- 
Martin Ambuhl (mambuhl AT earthlink DOT net)
Note: mambuhl AT tiac DOT net will soon be inactive