At least, It will help perl beginner not falling many pitfalls like above.
Perl beginners like you should start by reading perlintro and/or a book like "Learning Perl".

Perl operators are documented in full in perlop, but here are a few of
the most common ones:

Arithmetic
        +   addition
        -   subtraction
        *   multiplication
        /   division

Numeric comparison
        ==  equality
        !=  inequality
        <   less than
        >   greater than
        <=  less than or equal
        >=  greater than or equal

String comparison
        eq  equality
        ne  inequality
        lt  less than
        gt  greater than
        le  less than or equal
        ge  greater than or equal

    (Why do we have separate numeric and string comparisons? Because we
    don't have special variable types, and Perl needs to know whether to
    sort numerically (where 99 is less than 100) or alphabetically
    (where 100 comes before 99).