Why is nl_langinfo(CODESET) different from locale charmap?

This post originated from How do you get what kind of encoding your system uses in c/c++?

I tried using

nl_langinfo(CODESET)

but I got ANSI_X3.4-1968 instead of UTF-8 (which is what I get when typing: locale charmap开发者_高级运维). Am I using nl_langinfo() wrong? How should I use it?

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You need to first call

setlocale(LC_ALL, "");

nl_langinfo always gives information about the current locale.