What's the Fastest Way to Convert Integers to std::strings in C ?

C Performance Challenge: Integer to std::string Conversion

This challenge seeks to identify the most efficient algorithms for converting integers to std::strings in C . Previous approaches have been found to be lacking in performance.

To compete in this challenge, participants should provide code that performs integer-to-string conversions for 32-bit signed and unsigned integers, producing output as a std::string. The code should adhere to the following guidelines:

• Avoid tricks incompatible with threading or signals.
• Assume an ASCII character set.
• Test on INT_MIN for two's complement machines.
• Output should be identical to the canonical C version using stringstream (ideone.com/jh3Sa), or clearly understandable as the correct number.
• The code should compile and provide correct results on VC 2010 and g .

The provided code utilizes an array of pre-computed digit pairs, known as "digit_pairs", to achieve efficient conversions.

This solution significantly outperforms common methods such as sprintf and std::stringsstream, reducing computation time by an order of magnitude in some cases. It also demonstrates the benefits of minimizing std::string usage and returning by reference.

While the original challenge winner's code ran 350% faster than others on gcc, the provided solution surpasses that performance, establishing new speed benchmarks for this operation on both gcc and Visual C .

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