makestring.cpp

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#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <string>

std::string make_string( const char* fmt, ... ) {
    va_list ap;
    int lMessage = 256;
    char *message = ( char * ) malloc( lMessage * sizeof( char ) );
    *message = 0;
    int nChars = strlen( message );
    while ( 1 ) {
        /* Try to print in the allocated space. */
        va_start( ap, fmt );
#ifdef _GNU_SOURCE

        int n = vsnprintf ( message + nChars, lMessage - nChars - 1, fmt, ap );
#else

        int n = vsprintf ( message + nChars, fmt, ap );
#endif

        va_end( ap );
        /* If that worked, return else alloc more memory */
        if ( n > -1 && n < lMessage - nChars - 1 ) {
            std::string msg( message );
            free( message );
            return msg;
        } else {
            lMessage *= 2;
            message = ( char * ) realloc( message, lMessage * sizeof( char ) );
        }
    }
}

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