30 Input/output library [input.output]

30.5 Iostreams base classes [iostreams.base]

30.5.3 Class ios_­base [ios.base] Types [ios.types] Type ios_­base​::​openmode [ios::openmode]

using openmode = T3;

The type openmode is a bitmask type. It contains the elements indicated in Table 110.

Table 110openmode effects
ElementEffect(s) if set
app seek to end before each write
ate open and seek to end immediately after opening
binary perform input and output in binary mode (as opposed to text mode)
in open for input
out open for output
trunc truncate an existing stream when opening