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")
"MOTD"
Type: TextFile
Entire lines are handled using the readLine and writeLine operations.
l := readLine! f1
"root:x:0:root"
Type: String
writeLine!(f2, upperCase l)
"ROOT:X:0:ROOT"
Type: String
Use the endOfFile? operation to check if you have reached the end of the file.
while not endOfFile? f1 repeat
s := readLine! f1
writeLine!(f2, upperCase s)
Type: 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 write 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
"MOTD"
Type: TextFile
Finally, clean up.
)system rm /tmp/MOTD
See Also: