LISP - Symbols

Lisp - Comparison Operators

Quiz

Following table shows all the relational operators supported by LISP that compares between numbers. However unlike relational operators in other languages, LISP comparison operators may take more than two operands and they work on numbers only.

Assume variable A holds 10 and variable B holds 20, then −

Operator	Description	Example
=	Checks if the values of the operands are all equal or not, if yes then condition becomes true.	(= A B) is not true.
/=	Checks if the values of the operands are all different or not, if values are not equal then condition becomes true.	(/= A B) is true.
>	Checks if the values of the operands are monotonically decreasing.	(> A B) is not true.
<	Checks if the values of the operands are monotonically increasing.	(< A B) is true.
>=	Checks if the value of any left operand is greater than or equal to the value of next right operand, if yes then condition becomes true.	(>= A B) is not true.
<=	Checks if the value of any left operand is less than or equal to the value of its right operand, if yes then condition becomes true.	(<= A B) is true.
max	It compares two or more arguments and returns the maximum value.	(max A B) returns 20
min	It compares two or more arguments and returns the minimum value.	(min A B) returns 10

Example - Equality Comparison

Create a new source code file named main.lisp and type the following code in it.

main.lisp

; set a as 10
(setq a 10)
; set b as 20
(setq b 20)

; print equality of a and b
(format t "~% A = B is ~a" (= a b))
; print non-equality of a and b
(format t "~% A /= B is ~a" (/= a b))

Output

When you click the Execute button, or type Ctrl+E, LISP executes it immediately and the result returned is −

A = B is NIL
A /= B is T

Example - Size Comparison

Update file named main.lisp and type the following code in it.

main.lisp

; set a as 10
(setq a 10)

; set b as 20
(setq b 20)

; compare a with b for size and print result
(format t "~% A > B is ~a" (> a b))
(format t "~% A < B is ~a" (< a b))
(format t "~% A >= B is ~a" (>= a b))
(format t "~% A <= B is ~a" (<= a b))

Output

When you click the Execute button, or type Ctrl+E, LISP executes it immediately and the result returned is −

A > B is NIL
A < B is T
A >= B is NIL
A <= B is T

Example - Min/Max Computation

Update file named main.lisp and type the following code in it.

main.lisp

; set a as 10
(setq a 10)
; set b as 20
(setq b 20)

; compute max of a and b and print the result
(format t "~% Max of A and B is ~d" (max a b))

; compute min of a and b and print the result
(format t "~% Min of A and B is ~d" (min a b))

Output

When you click the Execute button, or type Ctrl+E, LISP executes it immediately and the result returned is −

Max of A and B is 20
Min of A and B is 10

lisp_operators.htm

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