format.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

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

#include <mrpt/core/format.h>
#include <cstdarg>

// A sprintf-like function for std::string
std::string mrpt::format_impl(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);
#if defined(_MSC_VER)
        result = ::vsnprintf_s(&buffer[0], length, _TRUNCATE, fmt, args);
#else
        result = ::vsnprintf(&buffer[0], length, fmt, args);
#endif
        va_end(args);

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

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