Verwendung von Variablen

Syntax:

VariableName

Beispiel:

genius> e
= 2.71828182846

To evaluate a variable by itself, just enter the name of the variable. This will return the value of the variable. You can use a variable anywhere you would normally use a number or string. In addition, variables are necessary when defining functions that take arguments (see „Definieren von Funktionen“).

Vervollständigung mit der Tabulatortaste

You can use Tab completion to get Genius to complete variable names for you. Try typing the first few letters of the name and pressing Tab.

Groß-/Kleinschreibung für Variablennamen

Bei Variablennamen wird zwischen Groß- und Kleinschreibung unterschieden. Das bedeutet, dass die Variablennamen hello, HELLO und Hello als unterschiedliche Variablen erkannt werden.

Setzen von Variablen

Syntax:

<identifier> = <value>
<identifier> := <value>

Beispiel:

x = 3
x := 3

To assign a value to a variable, use the = or := operators. These operators set the value of the variable and return the value you set, so you can do things like

a = b = 5

This will set b to 5 and then also set a to 5.

The = and := operators can both be used to set variables. The difference between them is that the := operator always acts as an assignment operator, whereas the = operator may be interpreted as testing for equality when used in a context where a Boolean expression is expected.

For more information about the scope of variables, that is when are what variables visible, see „Globale Variablen und Variablenbereiche“.

Eingebaute Variablen

GEL has a number of built-in ‘variables’, such as e, pi or GoldenRatio. These are widely used constants with a preset value, and they cannot be assigned new values. There are a number of other built-in variables. See „Konstanten“ for a full list. Note that i is not by default the square root of negative one (the imaginary number), and is undefined to allow its use as a counter. If you wish to write the imaginary number you need to use 1i.

Vorherige Ergebnisvariable

The Ans and ans variables can be used to get the result of the last expression. For example, if you had performed some calculation, to add 389 to the result you could do:

Ans+389