Re: Tabs As Syntax

Lawrence D'Oliveiro wrote this copyrighted missive and expects royalties:

On Fri, 22 Mar 2024 08:20:11 -0400, Chris Ahlstrom wrote:
>

operator << is useful with std::ostringstream when you want to avoid
having deal with allocating enough output space. Still, I use this a
lot:
 
    char temp[32];
    snprintf(temp, sizeof temp, "We have %d idiots here", idcount);
 
Sometime a printf specification is just easier to read.

>
I wrote this a long time ago, for use in some projects in C++. You can
tell it was a long time ago, from the checking for glibc versions:
>
std::string string_printf
  (
    const char * Format,
    ...
 )
  /* does an sprintf of its remaining arguments according to Format,
    returning the formatted result. */
  {
    std::string Result;
    char * TempBuf;
    ulong TempBufSize;
    TempBuf = nil;
    TempBufSize = 128; /* something reasonable to begin with */
    for (;;)
      {
        TempBuf = (char *)malloc(TempBufSize);
        if (TempBuf == nil)
            break;
        va_list Args;
        va_start(Args, Format);
        const long BufSizeNeeded = vsnprintf(TempBuf, TempBufSize, Format, Args);
          /* not including trailing null */
        va_end(Args);
        if (BufSizeNeeded >= 0 and BufSizeNeeded < TempBufSize)
          {
          /* the whole thing did fit */
            TempBufSize = BufSizeNeeded; /* not including trailing null */
            break;
          } /*if*/
        free(TempBuf);
        if (BufSizeNeeded < 0)
          {
          /* glibc < 2.1 */
            TempBufSize *= 2; /* try something bigger */
          }
        else
          {
          /* glibc >= 2.1 */
            TempBufSize = BufSizeNeeded + 1;
              /* now I know how much I need, including trailing null */
          } /*if*/
      } /*for*/
    if (TempBuf != nil)
      {
        Result.append(TempBuf, TempBufSize);
        free(TempBuf);
      } /*if*/
    return
        Result;
  } /*string_printf*/

You showed me yours.  Let me show you mine.  :-D

te<typename ... Args>
std::string string_format (const std::string & format, Args ... args)
{
    std::string result;
    size_t sz = std::snprintf(nullptr, 0, format.c_str(), args ...);
    if (sz > 0)
    {
        std::unique_ptr<char []> buf(new char[sz + 1]);
        std::snprintf(buf.get(), sz + 1, format.c_str(), args ...);
        result = std::string(buf.get(), buf.get() + sz);
    }
    return result;
}

Note the variadic template.

In C++20 you can apparently write

#include <format>
std::string result = std::format("{} {}!", "Hello", "world");


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