Finally, y is assigned the value of The use of equals for assignment dates back to Heinz Rutishauser 's language Superplan, designed from toand was particularly popularized by Fortran: A notorious example for a bad idea was the choice of the equal sign to denote assignment. But assignment alters the value of a variable, while equality testing tests whether two expressions have the same value.
In such languages, a variable is automatically declared the first time it is assigned to, with the scope it is declared in varying by language. Purely functional languages can provide an opportunity for computation to be performed in parallelavoiding the von Neumann bottleneck of sequential one step at time execution, since values are independent of each other.
If the type of the expression is identical to that of the variable, the result is saved in the variable.
Variant forms of assignment[ edit ] Certain use patterns are very common, and thus often have special syntax to support them. Single assignment is an example of name binding and differs from assignment as described in this article in that it can only be done once, usually when the variable is created; no subsequent reassignment is allowed.
In this case chain assignment can be implemented by having a right-associative assignmentand assignments happen right-to-left.