Converting double to char* in C++ with high performance

Question

My application needs to convert double values to char* to write to a pipe that accepts only characters. The usual ways of doing this are using the sprintf() functio

Answer 1

If you want to print any number that double type can support, use whatever library out there to do the job. It saves your sanity: Why does "dtoa.c" contain so much code?

If you want to print a subset of numbers in double type. For example, up to 4 digits after decimal point, and not more than 5 digits before decimal point, then you can round the number and convert to int type, before printing it out using division and mod. I can confirm the performance of this method.

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EDIT: If you original purpose is to send the data for communication, then sending the binary form of double will be the fastest and most accurate method (no possible loss of precision due to conversion). The way to do this is explained in other answers.