ToString.cc

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//=============================================================================
//  Computational Process Networks class library
//  Copyright (C) 1997-2006  Gregory E. Allen and The University of Texas
//
//  This library is free software; you can redistribute it and/or modify it
//  under the terms of the GNU Library General Public License as published
//  by the Free Software Foundation; either version 2 of the License, or
//  (at your option) any later version.
//
//  This library is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//  Library General Public License for more details.
//
//  The GNU Public License is available in the file LICENSE, or you
//  can write to the Free Software Foundation, Inc., 59 Temple Place -
//  Suite 330, Boston, MA 02111-1307, USA, or you can find it on the
//  World Wide Web at http://www.fsf.org.
//=============================================================================
#include "common_priv.h"
#include <cpn/utils/ToString.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

// This code was taken from an example of how
// to use vsnprintf in the unix man pages.
std::string ToString(const char *fmt, ...)
{   
    /* Guess we need no more than 100 bytes. */
    int n, size = 100;
    char *p, *np;
    va_list ap;
    std::string ret = "";
    p = (char*)malloc(size);
    if (p == NULL) {
        return ret;
    }

    while (1) {
        /* Try to print in the allocated space. */
        va_start(ap, fmt);
        n = vsnprintf(p, size, fmt, ap);
        va_end(ap);
        /* If that worked, return the string. */
        if (n > -1 && n < size) {
            ret = p;
            free(p);
            return ret;
        }
        /* Else try again with more space. */
        if (n > -1) {
                /* glibc 2.1 */
            size = n+1; /* precisely what is needed */
        }
        else {          /* glibc 2.0 */
            size *= 2;  /* twice the old size */
        }
        np = (char*)realloc (p, size);
        if (np == NULL) {
            free(p);
            return ret;
        } else {
            p = np;
        }
    }
}