Standard C++ Library Reference ISO/IEC (VERSION3)

characters and has not set the error indicator for the stream; otherwise, it returns a null pointer.
If it sets the error indicator, the array contents are indeterminate. The number of characters that
gets reads and stores cannot be limited. Use fgets instead.
_IOFBF
#define _IOFBF <integer constant expression>
The macro yields the value of the mode argument to setvbuf to indicate full buffering.
(Flush the stream buffer only when it fills.)
_IOLBF
#define _IOLBF <integer constant expression>
The macro yields the value of the mode argument to setvbuf to indicate line buffering.
(Flush the stream buffer at the end of a text line.)
_IONBF
#define _IONBF <integer constant expression>
The macro yields the value of the mode argument to setvbuf to indicate no buffering.
(Flush the stream buffer at the end of each write operation.)
L_tmpnam
#define L_tmpnam <integer constant expression > 0>
The macro yields the number of characters that the target environment requires for representing
temporary filenames created by tmpnam.
NULL
#define NULL <either 0, 0L, or (void *)0> [0 in C++]
The macro yields a null pointer constant that is usable as an address constant expression.