From Cppreference
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| FILE *fopen( const char *filename, const char *mode );
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Opens a file indicated by filename and returns a file stream associated with that file. mode is used to determine the file access mode.
[edit] Parameters
| filename
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-
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file name to associate the file stream to
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| mode
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-
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null-terminated character string determining file access mode
File access
mode string
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Meaning
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Explanation
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Action if file
already exists
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Action if file
does not exist
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| "r"
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read
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Open a file for reading
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read from start
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failure to open
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| "w"
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write
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Create a file for writing
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destroy contents
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create new
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| "a"
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append
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Append to a file
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write to end
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create new
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| "r+"
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read extended
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Open a file for read/write
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read from start
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error
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| "w+"
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write extended
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Create a file for read/write
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destroy contents
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create new
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| "a+"
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append extended
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Open a file for read/write
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write to end
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create new
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File access mode flag "b" can optionally be specified to open a file in binary mode. This flag has effect only on Windows systems.
On the append file access modes, data is written to the end of the file regardless of the current position of the file position indicator.
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[edit] Return value
opened file stream on success, NULL on failure
[edit] See also
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closes a file
(function)
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synchronizes an output stream with the actual file
(function)
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open an existing stream with a different name
(function)
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