c/io/std streams

Three text streams are predefined. These streams are implicitly opened and unoriented at program startup.

@1@ Associated with the standard input stream, used for reading conventional input. At program startup, the stream is fully buffered if and only if the stream can be determined to not refer to an interactive device. @2@ Associated with the standard output stream, used for writing conventional output. At program startup, the stream is fully buffered if and only if the stream can be determined to not refer to an interactive device. @3@ Associated with the standard error stream, used for writing diagnostic output. At program startup, the stream is not fully buffered.

What constitutes an interactive device is implementation-defined.

These macros are expanded to expressions of type.