A call to the setlocale subroutine must be made explicitly to change this default locale environment. The locale state is common to all threads within a process. Parameters Category Specifies a value representing all or part of the locale for a program. Depending on the value of the Locale parameter, these categories may be initiated by the values of environment variables with corresponding names. Affects the behavior of subroutines that format nonmonetary numeric values.
Locale Points to a character string containing the required setting for the Category parameter.
NULL Queries the current locale environment and returns the name of the locale. If a pointer to a string is given for the Locale parameter and the selection can be honored, the setlocale subroutine returns the string associated with the specified Category parameter for the new locale. If the selection cannot be honored, a null pointer is returned and the program locale is unchanged. If a null is used for the Locale parameter, the setlocale subroutine returns the string associated with the Category parameter for the program's current locale. The program's locale is not changed.