31 Input/output library [input.output]

31.5 Iostreams base classes [iostreams.base]

31.5.2 Class ios_base [ios.base]

31.5.2.2 Types [ios.types]

31.5.2.2.4 Type ios_base​::​openmode [ios.openmode]

Table 121: openmode effects [tab:ios.openmode]
Element
Effect(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
noreplace
open in exclusive mode
out
open for output
trunc
truncate an existing stream when opening