When to use eq and ==

[nfaber]

Hello all,

How can I tell for sure if the variable I am operating on is a string or an integer?

Can't 01 also be a string "01"??

Thanks

I got a Biz Degree! How the h*ll did I get here?

 

[PaulTEG]

Perl can determine the type of a variable depending on the operator and context

01 is technically 1
"01" is a string, but can be 1 in a numerical context

$var eq 1 is wrong
$var == 1 is right
$var eq "01" is right
$var == "01" is wrong

I hope I got that right
--Paul

cigless ...

 

[nfaber]

Ok Paul...how about this one:

my $date = "03-20-2005";

my ($month,$day,$year) = split (/-/, $date);

Is $month an integer or string?



I got a Biz Degree! How the h*ll did I get here?

 

[varakal]

String to my knowledge. In fact, a scalar. If you say

if ($month == 3)

it will accept and is true as internal conversion will be done.

 

[sfi]

if all the characters in the string are numeric use ==, else use eq.

 

[PaulTEG]

Nick,
in a word both
--Paul

cigless ...

 

[nfaber]

A little confusion here I see. Paul, you say both, does that mena either eq or == will work?



I got a Biz Degree! How the h*ll did I get here?

 

[audiopro]

Taking the value from a string will mean that the value of month is "03" but it also has a value of 3.
It depends how you wish to use the result.


Keith

http://www.studiosoft.co.uk

 

[MikeLacey]

Paul's quite right, if you have a string containing '01' it can be interpreted by Perl in a couple of ways.

As a string '01', so the test $var eq '01' will evaulate true.

As a number 01 or 1, so the test $var == 1 will evaluate true.

What won't work is this $var eq '1' or $var eq 1. Both of these compare $var to the string '1', which it won't match.

Mike

You cannot really appreciate Dilbert unless you've read it in the
original Klingon.

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