Hi monks，

I don't know implicit type exchange is a feature or a drawback of perl.In terms of me,I fall the same trap again and again ;)
Some days ago, many monks tell me oct and hex function only accept string no matter what you input. here
Yesterday,I wrote a script for fun and practice. here I found that user input 1(5 spaces before number) is equal to 1.Because of the last experience,I suspect that implict type exchange resulted in it.So I have a try: 
use strict;
use warnings;

my $num1 = 4;
my $str1 = "4";
my $str2 = "     4";
print "number \$num1 is equal to string \$str2!!\n"if $num1 == $str2;
print "number \$num1 is equal to string \$str1!!\n" if $num1 == $str1;
print "string \$num1 is equal to string str2 !!\n" if $num1 eq $str2;
print "string \$num1 is equal to string str1 !!\n" if $num1 eq $str1;



__OUTPUT__
number $num1 is equal to string $str2!!
number $num1 is equal to string $str1!!
string $num1 is equal to string str1 !!

[download]
Obviously,perl will truncate all spaces before number when it treats a string as a number.No offense,I was wondering why perl develper don't add type declaration(such as num,str).At least, It will help perl beginner not falling many pitfalls like above.
I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

In reply to implicit data type exchange by xiaoyafeng

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