Exit Zen
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string ID 10
type: paragraph
English
The [*File] concept abstracts access to files in the underlying file system. To support other platform interfaces, users may author their own [*File] types which meet these requirements.
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string ID 14
type: heading
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Associated Types
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string ID 19
type: heading
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Requirements
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string ID 21
type: paragraph
English
In this table:
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string ID 23
type: list
English
* `F` is a [*File] type
* `f` is an instance of `F`
* `p` is a value of type `char const*` which points to a null
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string ID 27
type: list
English
* `m` is an instance of [link beast.ref.boost__beast__file_mode `file_mode`]
* `n` is a number of bytes, convertible to `std::size_t`
* `o` is a byte offset in the file, convertible to `std::uint64_t`
* `b` is any non-const pointer to memory
* `c` is any possibly-const pointer to memory
* `ec` is a reference of type [link beast.ref.boost__beast__error_code `error_code`]
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string ID 34
type: table title
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Valid expressions
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string ID 34
type: table cell
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Operation
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string ID 34
type: table cell
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Default constructable
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string ID 34
type: table cell
English
Destructible. If `f` refers to an open file, it is first closed as if by a call to `close` with the error ignored.
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string ID 34
type: table cell
English
Returns `true` if `f` refers to an open file, `false` otherwise.
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string ID 34
type: table cell
English
If `f` refers to an open file, this function attempts to close the file. Regardless of whether an error occurs or not, a subsequent call to `f.is_open()` will return `false`. The function will ensure that `!ec` is `true` if there was no error or set to the appropriate error code if an error occurred.
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string ID 34
type: table cell
English
Attempts to open the file at the path specified by `p` with the mode specified by `m`. Upon success, a subsequent call to `f.is_open()` will return `true`. If `f` refers to an open file, it is first closed as if by a call to `close` with the error ignored. The function will ensure that `!ec` is `true` if there was no error or set to the appropriate error code if an error occurred.
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string ID 34
type: table cell
English
If `f` refers to an open file, this function attempts to determine the file size and return its value. If `f` does not refer to an open file, the function will set `ec` to `errc::invalid_argument` and return 0. The function will ensure that `!ec` is `true` if there was no error or set to the appropriate error code if an error occurred.
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string ID 34
type: table cell
English
If `f` refers to an open file, this function attempts to determine the current file offset and return it. If `f` does not refer to an open file, the function will set `ec` to `errc::invalid_argument` and return 0. The function will ensure that `!ec` is `true` if there was no error or set to the appropriate error code if an error occurred.
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string ID 34
type: table cell
English
Attempts to reposition the current file offset to the value `o`, which represents a byte offset relative to the beginning of the file. If `f` does not refer to an open file, the function will set `ec` to `errc::invalid_argument` and return immediately. The function will ensure that `!ec` is `true` if there was no error or set to the appropriate error code if an error occurred.
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string ID 34
type: table cell
English
Attempts to read `n` bytes starting at the current file offset from the open file referred to by `f`. Bytes read are stored in the memory buffer at address `b` which must be at least `n` bytes in size. The function advances the file offset by the amount read, and returns the number of bytes actually read, which may be less than `n`. If `f` does not refer to an open file, the function will set `ec` to `errc::invalid_argument` and return immediately. The function will ensure that `!ec` is `true` if there was no error or set to the appropriate error code if an error occurred. If an end-of-file condition is detected prior to reading any bytes, the function will ensure that `!ec` is `true` and the return value shall be 0.
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string ID 34
type: table cell
English
Attempts to write `n` bytes from the buffer pointed to by `c` to the current file offset of the open file referred to by `f`. The memory buffer at `c` must point to storage of at least `n` bytes meant to be copied to the file. The function advances the file offset by the amount written, and returns the number of bytes actually written, which may be less than `n`. If `f` does not refer to an open file, the function will set `ec` to `errc::invalid_argument` and return immediately. The function will ensure that `!ec` is `true` if there was no error or set to the appropriate error code if an error occurred.
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string ID 170
type: heading
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Exemplar
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string ID 174
type: heading
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Models
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