std::ios_base::openmode

From cppreference.com
typedef /*implementation defined*/ openmode;
static constexpr openmode app = /*implementation defined*/

static constexpr openmode binary = /*implementation defined*/
static constexpr openmode in = /*implementation defined*/
static constexpr openmode out = /*implementation defined*/
static constexpr openmode trunc = /*implementation defined*/

static constexpr openmode ate = /*implementation defined*/

Specifies available file open flags. It is a BitmaskType, the following constants are defined:

Constant Explanation
app seek to the end of stream before each write
binary open in binary mode
in open for reading
out open for writing
trunc discard the contents of the stream when opening
ate seek to the end of stream immediately after open

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