From: Martin Ambuhl <mambuhl AT earthlink DOT net>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Converting a string to a char *
Date: Sat, 25 Dec 1999 17:13:15 -0500
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Tom wrote:
> 
> I am trying to change a string to a char *.  I am using the function c_str()
> but I am having problems with it.
> 
> How would I go about assigning the new char * value to a char *?  For
> example, this is what I
> tried to do and it didn't work.  It gave me a (null) result when it should
> have said "test".  Thanks.
> 
> ______________________________
> 
> int main()
> {
> string s = "test";
> char *b;
> *b = *s.c_str();
> cout << b;
> return 0;
> }

#include <iostream>             /* mha - added */
#include <string>               /* mha - added */
#include <cstring>              /* mha - added */

int main()
{
    string s = "test";
    char *b;
    *b = *s.c_str();
    cout << "mha - the original code copied the value of \n"
        << " *s.c_str() [ *" << (void *)s.c_str() << "]:" 
        << *s.c_str() << ", s.c_str():" << s.c_str() << "\n"
        << " to *b [ *" << (void *)b << "]:" << *b 
        << ", b:" << b << "\n" << endl;
    
    b = s.c_str();  /* mha - discards constness, beware */
    cout << "mha - Now we copy the value of \n"
        << " s.c_str() [ *" << (void *)s.c_str() << "]:" 
        << s.c_str() << ", s.c_str():" << s.c_str() << "\n"
        << " to b [" << (void *)b << "]:" << b 
        << ", b:" << b << "\n" << endl;
    
    cout << "s.length() = " << s.length() << endl;
    b = new char[s.length()+1];
    strcpy(b, s.c_str());
    cout << "mha - now watch this, where we allocate some\n" 
        << "space for b to point to and copy s.c_str\n"  
        << " s.c_str() [ *" << (void *)s.c_str() << "]:" 
        << s.c_str() << ", s.c_str():" << s.c_str() << "\n"
        << " to b [" << (void *)b << "]:" << b 
        << ", b:" << b << endl;
    
    return 0;
}





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



-- 
Martin Ambuhl	mambuhl AT earthlink DOT net

What one knows is, in youth, of little moment; they know enough who
know how to learn. - Henry Adams

A thick skin is a gift from God. - Konrad Adenauer
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