perl - Why we can not use "le" in for loop and can use in "if condition" -

i've made program beginner. need clarify something! why m not able use "le" in loop given below i'm able use in "if condition". reason behind that. ?

print "type number upto series should run\n"; $var; $var = int<stdin>; chomp $var; ($i, $t); $x = 0; $y = 1;  if($var eq 1) {     print "\nyour series : $x\n"; } elsif($var eq 2){     print "\nyour series : $x $y\n"; } elsif($var ge 2) {     print "your series : $x $y ";     for($i = 1; $i le $var - 2; $i++) {         # why condition not working when i'm using "le"         # work when i'm using "<="         $t = $x + $y;         $x = $y;         $y = $t;          print "$t ";     }     print "\n"; } else {     print "error: enter valid postive integer\n"; } 

you free use le , <= like. should aware completely different operators.

numeric comparision operators

== !=  < <=  > >= <=> 

the equivalent string comparision operators are

eq ne lt le gt ge cmp 

strings , numbers converted each other needed. means example that

 3 ge 20 # true:  3 string-greater       20 11 le  2 # true: 11 string-less-or-equal  2 

because lexicographic ordering compares character character. using numeric operators when want treat contents of $variables numbers therefore preferable , yield correct results.

note perl translates between strings , numbers invisibly. advisable use warnings, helpful message when string can't represent number (e.g. "a").