How to debug in Perl ?

If it is a small program, you can use this way:

 

C:\Rebecca\script\perl>perl -d calculate.pl

 

Loading DB routines from perl5db.pl version 1.39_10

Editor support available.

 

Enter h or 'h h' for help, or 'perldoc perldebug' for morehelp.

 

main::(calculate.pl:3): my $number1 = 10;

  DB<1> $number1= 3   #you can change the number here

 

  DB<2> n #press n to execute next command

main::(calculate.pl:4): my $number2 = 6;

  DB<2> print$number1 # but you can see it didn’twork

10

  DB<3> $number1= 3 #change it again here, it willwork!!

 

  DB<4> print$number1 #see, it worked.

3

  DB<5> n

main::(calculate.pl:5): my $sum = $number1 + $number2;

  DB<5> print$number2

6

  DB<6> $number= -1 # I wanted to change number2 aswell, but I just type number by mistake….

 

  DB<7> n

main::(calculate.pl:7): print $sum, "\n";

  DB<7> print$sum

9 

  DB<8> q #quit the debug now