CODEWITHSUNDEEP
perlline-numbers
David Sykes
David Sykes

Reputation: 49822

How can I print the source line number in Perl?

Is it possible to get the current source line number in Perl?

The equivalent in C++ is __LINE__.

Upvotes: 39

Views: 39633

Answers (4)

Eugene Yokota
Eugene Yokota

Reputation: 95614

The __LINE__ literal is documented in the Special Literals section of the perldata man page.

print "File: ", __FILE__, " Line: ", __LINE__, "\n";

or

warn("foo");

Upvotes: 64

bigiain
bigiain

Reputation: 809

Note there's a gotcha with

perl -e 'warn("foo")'

Output:

foo at -e line 1.

If it ends with a newline it won't print the line number:

perl -e 'warn("foo\n")'

Output:

foo

This is documented in perldoc -f die, but it is perhaps easy to miss in the perldoc -f warn section's reference to die.

Upvotes: 8

user4155330
user4155330

Reputation: 19

"use Carp" and play with the various routines and you also get a stack; I am not sure if this way is better or worse than the "caller" method suggested by cnd.

I have used the LINE and FILE variables (and probably other similar variables) in C and Perl to show where I got in the code and other information when debugging, but I have seen little value outside a debug environment.

Upvotes: 2

cnd
cnd

Reputation: 1731

This prints out the line where you are, and also the "stack" (list of lines from the calling programs (scripts/modules/etc) that lead to the place you are now)

while(my @where=caller($frame++)) { print "$frame:" . join(",",@where) . "\n"; }

Upvotes: 2

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