Programming Perl, 4th Edition

chop

chop VARIABLE
chop LIST
chop

This function chops off the last character of a string variable and returns the character chopped. The chop function is used primarily to remove the newline from the end of an input record, and it is more efficient than using a substitution. If that’s all you’re doing, then it would be safer to use chomp, since chop always shortens the string no matter what’s there, and chomp is more selective.

You cannot chop a literal, only a variable. If you chop a LIST of variables, each string in the list is chopped:

@lines = `cat myfile`;
chop @lines;

You can chop anything that is an lvalue, including an assignment:

chop($cwd = `pwd`);
chop($answer = <STDIN>);

This is different from:

$answer = chop($tmp = <STDIN>);  # WRONG

which puts a newline into $answer because chop returns the character chopped, not the remaining string (which is in $tmp). One way to get the result intended here is with substr:

$answer = substr <STDIN>, 0, –1;

But this is more commonly written as:

chop($answer = <STDIN>);

In the most general case, chop can be expressed using substr:

$last_char = chop($var);
$last_char = substr($var, –1, 1, "");   # same thing

Once you understand this equivalence, you can use it to do bigger chops. To chop more than one character, use substr as an lvalue, assigning a null ...