9.81 TextFile

The domain TextFile allows FriCAS to read and write character data and exchange text with other programs. This type behaves in FriCAS much like a File of strings, with additional operations to cause new lines. We give an example of how to produce an upper case copy of a file.

This is the file from which we read the text.

f1: TextFile := open("/etc/group", "input")

\[\]

“/etc/group”

_{Type: TextFile}

This is the file to which we write the text.

f2: TextFile := open("/tmp/MOTD", "output")

\[\]

“/tmp/MOTD”

_{Type: TextFile}

Entire lines are handled using the readLinereadLineTextFile and writeLinewriteLineTextFile operations.

l := readLine! f1

\[\]

“root:x:0:root”

_{Type: String}

writeLine!(f2, upperCase l)

\[\]

“ROOT:X:0:ROOT”

_{Type: String}

Use the endOfFile?endOfFile?TextFile operation to check if you have reached the end of the file.

while not endOfFile? f1 repeat
    s := readLine! f1
    writeLine!(f2, upperCase s)

Void

The file f1 is exhausted and should be closed.

close! f1

\[\]

“/etc/group”

_{Type: TextFile}

It is sometimes useful to write lines a bit at a time. The writewriteTextFile operation allows this.

write!(f2, "-The-")

\[\]

“-The-“

_{Type: String}

write!(f2, "-End-")

\[\]

“-End-“

_{Type: String}

This ends the line. This is done in a machine-dependent manner.

writeLine! f2

\[\]

“”

_{Type: String}

close! f2

\[\]

“/tmp/MOTD”

_{Type: TextFile}

Finally, clean up.

)system rm /tmp/MOTD

For more information on related topics, see FileXmpPage , KeyedAccessFileXmpPage , and LibraryXmpPage .