BIF 101 Last Lab – Array Explorations – December 4, 2008
Goal: Finish as many of these exercises as you can. They will help boost your lab grade!
1. oneline.pl
Write a program that inputs one line from a file (as a string), chops off the carriage
return, uses a regular expression to remove punctuation, and prints out the line. You can
copy the lrr.txt file from the class web page or create a multi-line text file yourself. One
suggest is to create the file from some song lyrics – find them on the Internet.
To get input from a file into a program you need to open the file, read from the file, then
close the file. Here is an example of doing that:
# the open command names a file variable (MYINPUTFILE) and a file (here it’s lrr.txt)
open(MYINPUTFILE, "lrr.txt");
# input from a file rather than from the command line in the window use the file variable
$line = <MYINPUTFILE>;
# close the file when you’re done reading
close(MYINPUTFILE);
The regular expression will look something like this:
/[\.;:,”]//g
2. alllines.pl
Instead of just inputting one line input the entire file into an array, where each array
element is a line from the file. Then print out what you’ve read in, line by line. To read
in an entire file all at once use the following:
@lines = <MYINPUTFILE>;
The only difference from above is that you read the file into an array variable.
Now you’ll need to loop through the array called @lines and print a line at a time, you
can do this easily with a foreach loop:
foreach $line (@lines)
{
#don’t forget to chomp off the carriage return
#make sure to remove the punctuation from the line here with your regex
print “$line\n”;
}
