Interpreting values alternately as $trings and Integers = confused response by Perl

jerrygarciuh has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Interpreting values alternately as $trings and Integers = confused response by Perl by ariels (Curate) on Apr 14, 2002 at 19:56 UTC
If you write "`$ary[0] = '12'`", you assign the value "`'12'`" to `$ary[0]`. Perhaps you were thinking of "`$ary[0] == '12'`"?	[reply] [d/l] [select]
(elbie): Interpreting values alternately as $trings and Integers = confused response by Perl by elbie (Curate) on Apr 14, 2002 at 20:07 UTC
Note that perl has two different kinds of comparison operators, one for strings (`eq`) and one for numerical values (`==`) Minor point, but you should probably use `$arr[0] == 12` to get a true numerical comparison. i.e. Drop the quotes. elbieelbieelbie	[reply] [d/l]
Re: (elbie): Interpreting values alternately as $trings and Integers = confused response by Perl by premchai21 (Curate) on Apr 15, 2002 at 01:09 UTC
I agree that the quotes should probably be removed, but for reasons of clarity -- that is, people are likely to glance at the code and accidentally interpret the == as an eq due to seeing quotes. == does "true numerical comparison" whether or not there are quotes there; the string gets converted to a number for the ==, and it DWYM.	[reply]
Re: Interpreting values alternately as $trings and Integers = confused response by Perl by Juerd (Abbot) on Apr 14, 2002 at 20:07 UTC
`} elsif ($ary[0] = '12') {` and found that $ary[0] was being assigned a value of 12. `Relational operators String Number Equal eq == Not equal ne != Greater gt > Greater or equal ge >= Less lt < Less or equal le <= Compare cmp <=>` [download] As you can see, `=` is not a relational operator that test equality. What is it then? It's the assignment operator. You assigned 12 to $ary[0], and an assignment returns the assigned value, so the entire `$ary[0] = '12'` expression returns `12`, which evaluates to true in boolean context. You probably meant `==` or `eq`, depending on how you want to see things. If you use `==`, drop the quotes so that Perl doesn't have to convert the string 12 to the number 12. - Yes, I reinvent wheels. - Spam: Visit eurotraQ.	[reply] [d/l] [select]
jerrygarciuh flogs-self with the trout of rebuke. by jerrygarciuh (Curate) on Apr 14, 2002 at 21:40 UTC
jerrygarciuh flogs his braindead idiot self with the trout of rebuke. Sorry for inane question, BTW I don't know how I missed in in my perl -c checks earlier but I just did get a warning that I probably intended to use == when I ran a command line check and a second instance of this mistake cropped up. Slap, slap, slap. Blushing, jg _____________________________________________________ Think a race on a horse on a ball with a fish! TG	[reply] [d/l]
Re: Interpreting values alternately as $trings and Integers = confused response by Perl by CukiMnstr (Deacon) on Apr 14, 2002 at 20:37 UTC
he. I guess you really meant the "Sober Monx" part ;-)	[reply]
Re: Interpreting values alternately as $trings and Integers = confused response by Perl by Anonymous Monk on Apr 15, 2002 at 10:55 UTC
It looks like you used "`=`", which is assignment, hence Perl is assigning the value 12 to your array element. On the other hand, your if statement was trying to check if `$ary[0]` was equal to 12, so you should have used "`==`" (with no quotes, of course!) as follows : `} elsif ($ary[0] == ...` Hope this helps. Emanuela.	[reply] [d/l] [select]


Clear questions and runnable code get the best and fastest answer
	PerlMonks