eq (AutoLISP)

Determines whether two expressions are identical

Supported Platforms: Windows and Mac OS

Signature

(eq expr1 expr2)

expr1

Type: Integer, Real, String, List, Ename (entity name), T, or nil

The expression to be compared.

expr2

Type: Integer, Real, String, List, Ename (entity name), T, or nil

The expression to compare with expr1.

Return Values

Type: T or nil

T if the two expressions are identical; otherwise nil.

Remarks

The eq function determines whether expr1 and expr2 are bound to the same object (by setq, for example).

Examples

Given the following assignments:

(setq f1 '(a b c)) 
(setq f2 '(a b c)) 
(setq f3 f2)

Compare f1 and f3:

(eq f1 f3)
nil

eq returns nil because f1 and f3, while containing the same value, do not refer to the same list.

Compare f3 and f2:

(eq f3 f2)
T

eq returns T because f3 and f2 refer to the same list.