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Global Variables

The Microsoft run-time library provides the following global variables. These global variables have been deprecated for the more secure functional versions, which should be used in place of the global variable (except _pgmptr and _wpgmptr).



_acmdln, _tcmdln, _wcmdln

Contains the command line.


Controls memory heap granularity

_daylight, _dstbias, _timezone, and _tzname

Adjust for local time; used in some date and time functions

errno, _doserrno, _sys_errlist, and _sys_nerr

Store error codes and related information

_environ, _wenviron

Pointers to arrays of pointers to strings that constitute process environment


Specifies whether information regarding open files of a process is passed to new processes


Sets default file-translation mode


The array of stdio control structures.

_pctype, _pwctype, _wctype, _mbctype, _mbcasemap

Contain information used by the character classification functions.

_pgmptr, _wpgmptr

Initialized at program startup to value such as program name, filename, relative path, or full path