Cross Ref > Operators

Languages Focus

Common assignment operators for languages include =, ==, and :=. An assignment operator allows you to assign a value to a variable. The value can be a literal value like "Mike" or 42 or the value stored in another variable or returned by a function.

Perl:   = Perl assignment operators: = Assignment $x = 8; += Addition $x += 8; -= Substraction $x -= 8; *= Muliplication $x *= 8; /= Division $x /= 8; %= Modulus $x %= 8; **= Exponent $x **= 8; Syntax Example: $FullName = "Randy Spitz"; $Age = 38;	PHP:   = PHP uses = for it's assignment operator. Syntax Example: $fullname = "Randy Spitz"; $age = 38;

General Info: Round Floating Point Numbers

When comparing floating point numbers, make sure you round to an acceptable level of rounding for the type of application you are using.

Languages Focus

A comparison operator compares two values either literals as in "Hello" and 3 or variables as in X and Counter. Most languages use the same operators for comparing both numbers and strings. Perl, for example, uses separate sets of comparison operators for numbers and strings.

Perl:   ==, != Common comparison operators: == equal != not equal < less than > greater than <= less than or equal >= greater than or equal Perl also offers additional string comparison operators: eq string equals ne string not equal lt string less than gt string greater than le string less than or equal ge string greater than or equal Syntax Example: #Does Perl evaluate the math correctly? No! if ((.1 + .1 + .1) == .3) { print("Correct<br>"); } else { print("Not correct<br>"); }

PHP:   ==, != or <> Common comparison operators: == equal != or <> not equal < less than > greater than <= less than or equal >= greater than or equal PHP 4 and above also offers === for indentical (equal plus same type) and !== for not identical (not equal or not same type). Syntax Example: //Does PHP evaluate the math correctly? No! if (.1 + .1 + .1 == .3) { echo "correct"; } else { echo "not correct"; }

Languages Focus

Logical operators perform conditional and, or, and not operations. Some languages support both binary logical operators that link two and unary logical operators negate (make opposite) the truth value of its argument. Finally, some languages short circuit logic. For example, with this or that, if this is an expression returning true, then that is never executed.

Perl:  Perl logical operators: && or and and, as in this and that || or or or, as in this or that ! Not, as in Not This Syntax Example: #Given expressions a, b, c, and d: if !((a && b) && (c || d)) {   #Do something. }	PHP:   and, &&, or, ||, !, Xor PHP logical operators: and, && and, as in this and that or, || or, as in this or that ! Not, as in Not This Xor either or, as in this or that but not both Syntax Example: #Given expressions a, b, c, and d: if !((a && b) && (c || d)) {   #Do something. };

General Info: Unary Operator

An operation with only one operand (a single input). Common unary operators include + plus, - minus, and bitwise not. Some operators can function as both unary and binary operators. For example, + and - operators can serve as either.

Languages Focus

What unary operators are supported in additoin to the standard plus, minus, and bitwise not.

Perl:  An operation with only one operand (a single input). The following are the Perl unary operators: !, -, ~, +, \, &, and *. ! performs logical negation which is "not" - performs arithmetic negation if the operand is numeric. ~ performs bitwise negation, that is 1's complement. + has no semantic effect whatsoever, even on strings. \ creates a reference to whatsoever follows. & Address of operator. * Dereference address operator.  Perl Unary Operators

PHP:  A unary operator operates on only one value. PHP Examples: ! negation operator ++ increment operator -- decrement operator  PHP Unary Operators