Marc Gurevitx: /* Equality */

2023-11-22T15:10:36Z

Equality

Marc Gurevitx: Details on comparison

2023-11-17T16:10:39Z

Details on comparison

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Comparison operators: <c> == </c>, <c> != </c>, <c> > </c>, <c> < </c>, <c> >= </c>, <c> <= </c>.

== Equality ==

The operator <c>==</c> tests for equality; the operator <c>!=</c> is the negation of equality. These operators always result in [[true]] or [[false]]. Both can be applied to ''any'' values, not necessarily of the same type. If the values have different types, they're considered not equal. Otherwise, they're compared according to their types:

* [[null]] is equal to itself
* [[number]]s and [[string]]s are compared in the usual way. (Unlike in some other languages, <c>0 == "0"</c> is false.)
* [[list]]s are equal if they contain equal elements
* [[map]]s are equal if they contain equal key/value pairs
* [[funcRef]]s are equal if they reference the same function
* The special value [[NaN]] is not equal to anything, even to itself

To compare [[list]]s and [[map]]s by reference, use [[refEquals]] function.

== Relational operators ==

Comparisons <c> > </c>, <c> < </c>, <c> >= </c>, <c> <= </c> are defined for numbers (arithmetic comparison) and strings (alphabetic comparison). These cases result in [[true]] or [[false]].

For other data types or for operands of different data types they return [[null]].

If the operands are a number and a [[null]], they substitute [[null]] with <c>0</c> (resulting in [[true]] or [[false]]).

If the operands are a string and a [[null]], it considers the string being always greater than [[null]] (resulting in [[true]] or [[false]]).

All six operators support [[Operators#Comparison_Operators|chaining]].

=== Examples ===

<ms>
print null == null // prints 1
print 0 != "0" // prints 1
print 13 < 42 <= 420 // prints 1
print 2 < 15 // prints 1
print "2" < "15" // prints 0, alphabetic comparison
print 0/0 == 0/0 // prints 0, NaN != NaN
print [1, 2, 3] == [1, 2, 3] // prints 1
print 0 != null and 0 >= null and 0 <= null // prints 1 :)
</ms>

[[Category:Language]]

@@ Line 3: / Line 3: @@
 == Equality ==
-The operator <c>==</c> tests for equality; the operator <c>!=</c> is the negation of equality. These operators always result in [[true]] or [[false]]. Both can be applied to ''any'' values, not necessarily of the same type. If the values have different types, they're considered not equal. Otherwise, they're compared according to their types:
+The operator <c>==</c> tests for equality; the operator <c>!=</c> is the negation of equality. These operators always result in [[true]] or [[false]] (or in some cases of incompatible types - <c>null</c>). Both can be applied to ''any'' values, not necessarily of the same type. If the values have different types, they're considered not equal. Otherwise, they're compared according to their types:
 * [[null]] is equal to itself

Comparison - Revision history

Marc Gurevitx: /* Equality */

Marc Gurevitx: Details on comparison