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Constants (Delphi and PHP Cross Reference Guide)

By Mike Prestwood

Delphi versus PHP: A side by side comparison between Delphi and PHP.

Language Basics

Language basics is kind of a catch all for absolute beginner stuff. The items (common names) I chose for language basics is a bit random and include items like case sensitivity, commenting, declaring variables, etc.

Constants

[Other Languages]

General Info: Computer Language Constants

A constant is just like a variable (it holds a value) but, unlike a variable, you cannot change the value of a constant.

Delphi: Const kPI: Double=3.1459;

In Delphi, you define constants similar to how you define variables but use the Const keyword instead of the Var keyword. Declare global constants in a unit's interface section and unit constants (scope limited to unit) in the implementation section. Declare local constants above the begin..end block.

Syntax Example:

Const

  kFeetToMeter: Double = 3.2808;

  kMeterToFeet: Double = .3048;

  kName: String = "Mike";

//Local constants:

procedure SomeProcedure;

const

  kPI: Double=3.1459;

begin

end;

Delphi Constants (Const kPI: Double=3.1459;) 1 certification question.

PHP: define

In PHP, you declare constants using the define keyword:

define("CONST_NAME", "Value");

Constants in PHP are case sensitive. A common standard in PHP is to use all-uppercase letters, with underscores to separate words within the name.

Syntax Example:

define('FULL_NAME', 'Mike Prestwood');
define("AGE", 25);

echo "Your name is " . FULL_NAME . ".";
echo "You are " . AGE . ".";

PHP Constants (define)