File streams are streams associated with files. An input file stream
reads the characters it delivers from a file, an output file stream
prints the characters it receives to a file. The following functions can
be used to create such streams. They return fail if an error occurred,
in this case LastSystemError (see LastSystemError) can be used to get
information about the error.
InputTextFile( name-file ) O
InputTextFile( name-file ) returns an input stream in the category
IsInputTextStream that delivers the characters from the file
name-file.
OutputTextFile( name-file, append ) O
OutputTextFile( name-file, append ) returns an output stream in the
category IsOutputTextFile that writes received characters to the file
name-file. If append is false, then the file is emptied first,
otherwise received characters are added at the end of the list.
Example
# use a temporary directory gap> name := Filename( DirectoryTemporary(), "test" );; # create an output stream, append output, and close again gap> output := OutputTextFile( name, true );; gap> AppendTo( output, "Hallo\n", "You\n" ); gap> CloseStream(output); # create an input, print complete contents of file, and close gap> input := InputTextFile(name);; gap> Print( ReadAll(input) ); Hallo You gap> CloseStream(input); # append a single line gap> output := OutputTextFile( name, true );; gap> AppendTo( output, "AppendLine\n" ); # close output stream to flush the output gap> CloseStream(output); # create an input, print complete contents of file, and close gap> input := InputTextFile(name);; gap> Print( ReadAll(input) ); Hallo You AppendLine gap> CloseStream(input);
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GAP 4 manual