learning perl review ch2

scalar:

    1.233, 2E-3, 3e45
        # exponential float
    123_123_234
        # integer with underscore
    0377, 0xff, 0b1111
        # octal => 0, hexadecimal => 0x, binary => 0b
    "hello,"."world!"
        # concatenate with .
    "hello" x 3
        # repeat 3 time with x
    "20fred" * 3
        # ignore string when transform
    $str = $str . "blah";  ===  $str .= "blah";
    $int = $int ** 3;  ===  $int **= 3;
        # binary assignment operator
    ${word}blah~
        # insert variable with dereference brace
    eq == | ne != | <  lt | >  gt | <= le | >= ge
        # string comparison operator
    
        # return with \n at line end
    defined($var)
        # return true or false

initial parameters (perl -M)

    use warnings;
    use diagnostics;