Computer Programming/Variables

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This computer programming article is available in pseudocode and Ada.

Variables are references that stand in for a value that is contained at a certain memory address.

Variables are said to have a value and may have a data type. If a variable has a type, then only values of this type may be assigned to it. Variables do not always have a type.

A value can have many values of many different types: integers (7), ratios (1/2), (approximations of) reals (10.234), complex numbers (4+2i), characters ('a'), strings ("hello"), and much more.

Different languages use different names for their types and may not include any of the above.

Assignment statements[edit source]

An assignment statement is used to set a variable to a new value.

An assignment statements in wikibook pseudocode is written as let variable := value.

 let X := 10

The example set the variable X to the integer value of 10. The assignment statement overwrites the contents of the variable and the previous value is lost.

In some languages, before a variable can be used, it will have to be declared, where the declaration specifies the type.

But this is not needed in wikibook pseudocode.

Uses[edit source]

Variables store everything in your program. The purpose of any useful program is to modify variables.