Operators

Arithmetic Operators

Symbol	Meaning	Example
`+`	Addition	`$a = $b + $c;`
`*`	Multiplication	`$temp = $in * 9.81;`
`/`	Division	`print "Age = ", $b / 2;`
`%`	Modulo	`$rem = $a % $b;`
`**`	Exponentiation	`$cubic = $x**3;`
`--`	Pre/post Decrement	`$num_left--;`
`++`	Pre/post Increment	`$count++;`
`\|, &, ^`	Bitwise `OR`, `AND`, `XOR`	`$nibble = $value & 0xff;`

String Operators

Symbol	Meaning	Example
`.`	Concatenation	`$path = $dir . $name;`
`x`	Multiplication	`print "Header", '-' x 60`

Logical Operators

Symbol	Meaning	Example
`==, !=, <, >, <=, >=`	Numeric Comparators	`$count++ if ($val > 0);`
`eq, ne`	String Comparators	`print "Try again >" if ($ans ne 'y');`
`=~, !~`	Pattern Match	`print "Try again >" if ($ans !~ /y/i);`
`\|\|, &&, or, and`	Logic	`print "yes" if ($a > 0 && $a < $max);`
`?:`	Conditional	`$max = ($a > $b) ? $a : $b;`

Assignment Operators

The following assignment operators are recognized: **= += *= &= <<= &&= -= /= |= >>= ||= .= %= ^= x=

File Test Operators

Symbol	Meaning
`-r`	File is readable by effective uid/gid.
`-w`	File is writable by effective uid/gid.
`-x`	File is executable by effective uid/gid.
`-o`	File is owned by effective uid.
`-R`	File is readable by real uid/gid.
`-W`	File is writable by real uid/gid.
`-X`	File is executable by real uid/gid.
`-O`	File is owned by real uid.
`-e`	File exists.
`-z`	File has zero size.
`-s`	File has non-zero size (returns size).
`-f`	File is a plain file.
`-d`	File is a directory.
`-l`	File is a symbolic link.
`-p`	File is a named pipe (FIFO).
`-S`	File is a socket.
`-b`	File is a block special file.
`-c`	File is a character special file.
`-t`	Filehandle is opened to a tty.
`-u`	File has setuid bit set.
`-g`	File has setgid bit set.
`-k`	File has sticky bit set.
`-T`	File is a text file.
`-B`	File is a binary file (opposite of `-T`).
`-M`	Age of file in days when script started.
`-A`	Same for access time.
`-C`	Same for inode change time.

Misc

Code	Meaning	Example
`..`	Range Operator	`@alpha = ('a' .. 'z');`

Operator Precedence

Borrowed from the Perl online documentation: Perl operators have the following associativity and precedence, listed from highest precedence to lowest. Note that all operators borrowed from C keep the same precedence relationship with each other, even where C's precedence is slightly screwy. (This makes learning Perl easier for C folks.)



    left	terms and list operators (leftward)
    left	->   
    nonassoc	++ --
    right	**
    right	! ~ \ and unary + and -
    left	=~ !~ 
    left	* / % x
    left	+ - .
    left	<< >>
    nonassoc	named unary operators
    nonassoc	< > <= >= lt gt le ge
    nonassoc	== != <=> eq ne cmp
    left	&
    left	| ^
    left	&&
    left	||
    nonassoc	..
    right	?:
    right	= += -= *= etc.
    left	, => 
    nonassoc	list operators (rightward)
    left	not
    left	and
    left	or xor

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Last Modified: $Date: 1997/09/18 08:48:45 $