What's the Fastest Way to Convert an Integer to a std::string in C ?

C Performance Challenge: Integer to std::string Conversion

This challenge seeks to find the most efficient code for converting an integer to a std::string in C . Despite numerous existing methods, none have proven to be particularly efficient, prompting the author to present his own competitive approach.

To participate in the challenge, the code should:

• Convert signed and unsigned 32-bit integers into decimal.
• Produce output as a std::string.
• Comply with specified rules, including compatibility with threading and signals.
• Ideally, match the canonical C output using stringstream.

The author invites performance benchmarks from different platforms and compilers, utilizing MB/s throughput as the standard unit of measurement. Additionally, any instances of undefined behavior or invalid input handling would be greatly appreciated.

After extensive testing, the speed champions for gcc and Visual C emerged as:

• For gcc: Eugene Smith, at 8x faster than sprintf.
• For Visual C : Timo, at 15x faster than sprintf.

The author notes that code that outperforms sprintf by an order of magnitude has been discovered, while ostringstream lags far behind.

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