c++ - What is the _REENTRANT flag?

Question

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

which compiling a multithreaded program we use gcc like below:

gcc -lpthread -D_REENTRANT -o someprogram someprogram.c

what exactly is the flag -D_REENTRANT doing over here?

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1 Answer

深蓝 · Answer 1 · 2021-10-23T19:02:52+0000

Defining _REENTRANT causes the compiler to use thread safe (i.e. re-entrant) versions of several functions in the C library.

You can search your header files to see what happens when it's defined.