Global Variables
The Microsoft run-time library provides the following global variables.
| Variable | Description |
| _amblksiz | Controls memory heap granularity |
| daylight, _timezone, _tzname | Adjust for local time; used in some date and time functions |
| _doserrno, errno, _sys_errlist, _sys_nerr | Store error codes and related information |
| _environ, _wenviron | Pointers to arrays of pointers to strings that constitute process environment |
| _fileinfo | Specifies whether information regarding open files of a process is passed to new processes |
| _fmode | Sets default file-translation mode |
| _osver, _winmajor, _winminor, _winver | Store build and version numbers of operating system |
| _pgmptr, _wpgmptr | Initialized at program startup to value such as program name, filename, relative path, or full path |