How can I print source line number in Perl?-CodePudding

Is it possible to get the current source line number in Perl? The equivalent in C is __LINE__.

CodePudding user response：

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

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

warn("foo");

CodePudding user response：

Note there's a gotcha with

$ perl -e'warn("foo")'
foo at -e line 1.

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

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

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

CodePudding user response：

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"; }

CodePudding user response：

"use Carp" and play with the various routines and you also get a stack - 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 have seen little value outside a debug environment.