About
The Equality operators model the Equivalence relation:
- equality
- is parallel to (for affine spaces)
- is in bijection with
- isomorphy
The Equality operators are a subset of the comparison operator.
The = symbol was designed to be two lines of visibly equal length.
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Usage
The equality operators as comparison operator are used in predicate (condition) expression in order to:
- and execute conditionally.
Operator
Equality operator
| Operation | Description |
|---|---|
| == | loose-equals, same value, two different Type such as '2' in number of '2' as string are loose-equals |
| === | strict-equals, same value, same type |
| != | loose not-equals |
| <> | loose not-equals (should be deprecated) |
| !== | strict not-equals |
| is | object identity |
| is not | negated object identity |
The operator = is generally not a comparison operator but an assignment operator
Mathematics
- Approximately equal
<MATH> a \approx b </MATH>
Evil in loop predicate
The equality operator is evil in a loop predicate.
The common error is to find a == in the code where there should have been a >= or a <=
See: