Полезная информация

Programming Perl

Programming PerlSearch this book
Previous: 3.2.13 chompChapter 3
Functions
Next: 3.2.15 chown
 

3.2.14 chop

chop VARIABLE
chop LIST
chop

This function chops off the last character of a string and returns the character chopped. The chop operator is used primarily to remove the newline from the end of an input record, but is more efficient than s/\n$//. If VARIABLE is omitted, the function chops the $_ variable. For example:

while (<PASSWD>) {
    chop;   # avoid \n on last field
    @array = split /:/;
    ...
}

If you chop a LIST, each string in the list is chopped:

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

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

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

Note that 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>);

To chop more than one character, use substr as an lvalue, assigning a null string. The following removes the last five characters of $caravan:

substr($caravan, -5) = "";

The negative subscript causes substr to count from the end of the string instead of the beginning.


Previous: 3.2.13 chompProgramming PerlNext: 3.2.15 chown
3.2.13 chompBook Index3.2.15 chown