 Open in App
Not now

# When Construct in LISP

• Last Updated : 09 Nov, 2021

In this article, we will discuss the when construct. The when is a decision-making statement used to specify the decisions. It is similar to conditional statements.

Syntax:

`(when (condition) (statements) )`

where,

1. condition is a test statement used to test
2. statements are the actions that will depend on the condition

Example 1: LISP Program to check the number is equal to 50 or not

## Lisp

 `;set number to ``50``(setq number ``50``)`` ` `;condition check the given number is ``equal` `to ``50` `(``when` `(``=` `number ``50``)`` ` `;statement``  ``(``format` `t` `"Equal to 50"``)``   ``)`

Output:

`Equal to 50`

Example 2: LISP Program to check the given number with comparison operators

## Lisp

 `;set number to ``50``(setq number ``50``)`` ` `;condition check the given number is ``equal` `to ``50` `(``when` `(``=` `number ``50``)`` ` `;statement``  ``(``format` `t` `"Equal to 50"``)``   ``)``(terpri)``;set number to ``150``(setq number ``150``)`` ` `;condition check the given number is greater than or ``equal` `to ``50` `(``when` `(>``=` `number ``50``)`` ` `;statement``  ``(``format` `t` `"greater than or Equal to 50"``)``   ``)``(terpri)  ``   ``;set number to ``10``(setq number ``10``)`` ` `;condition check the given number is less than or ``equal` `to ``50` `(``when` `(<``=` `number ``50``)`` ` `;statement``  ``(``format` `t` `"less than or Equal to 50"``)``   ``)`

Output:

```Equal to 50
greater than or Equal to 50
less than or Equal to 50```

My Personal Notes arrow_drop_up