format.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#include "base-precomp.h"  // Precompiled headers

#include <mrpt/utils/utils_defs.h>
#include <mrpt/system/os.h>
#include <mrpt/system/memory.h>

#include <cstdarg>

// A sprintf-like function for std::string
std::string mrpt::format(const char* fmt, ...)
{
        if (!fmt) return std::string();

        int result = -1, length = 2048;
        std::string buffer;
        while (result == -1)
        {
                buffer.resize(length);

                va_list args;  // This must be done WITHIN the loop
                va_start(args, fmt);
                result = mrpt::system::os::vsnprintf(&buffer[0], length, fmt, args);
                va_end(args);

                // Truncated?
                if (result >= length) result = -1;
                length *= 2;

                // Ok?
                if (result >= 0)
                {
                        buffer.resize(result);
                }
        }

        return buffer;
}