These generic-text constant, global variable, and standard-type mappings are defined in TCHAR.H and depend on whether the constant _UNICODE or _MBCS has been defined in your program.
Generic-Text Constant and Global Variable Mappings
| Generic-text - object name | SBCS (_UNICODE, _MBCS not defined) | _MBCS defined | _UNICODE defined | 
|---|---|---|---|
| _TEOF | EOF | EOF | WEOF | 
| _tenviron | _environ | _environ | _wenviron | 
| _tpgmptr | _pgmptr | _pgmptr | _wpgmptr |