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FOPEN
. Summary
fopen(str <name>, str <mode>);
. Description
The fopen function is used to open a disk file for reading and/or
writing. The file to be opened is given by <name>. <mode> is a
string indicating for what use the file should be opened. Legal val-
ues for mode are:
"r" Opens for reading
"w" Opens for writing (truncates any existing file with
the same name)
"a" Opens for appending (writing at the end of the file).
Creates the file if it doesn't exist.
"r+" Opens for reading and writing. Initial position at
the beginning of the file (the file must already ex-
ist).
"w+" Opens for reading and writing. If the file exists its
contents are destroyed.
"a+" Opens for reading and appending. Creates the file if
it doesn't exist.
If a file is opened for both reading and writing (when "r+", "w+",
or "a+" are used as the mode), an fseek operation is necessary be-
fore switching from one to the other.
. Return Value
The fopen function returns a 'handle' which is an integer number by
which this file is to be referred to until it is finally closed. A
value of 0 is returned if the file can not be opened (because it
doesn't exist, because a disk error occurred, or because there are
no more file handles available). Only up to 8 files may be opened at
a time. It is therefore very important to close open files if they
are no longer needed and when a script is done, or else all avail-
able file handles will become used up.
. Example
int f;
f = fopen("data.txt", "r"); // open the file for reading
if (f == 0)
prints("Error opening file!");
See Also:
fclose
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