[1][2] The functions are used in multilingual programs to adapt to the specific locale.
These settings affect the behaviour of input/output functions in the C Standard Library.
[3] C localization functions and types are defined in locale.h (clocale header in C++).
[6] The functions alter the behavior of printf/scanf/strtod which are often used to write saved data to a file or to other programs.
Most large-scale software forces the locale to "C" (or another fixed value) to work around these problems.