| assignment | statement |
| Syntax | An assignmentStatement is:
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| Description | An assignment statement calculates the value of the expression (expn) and assigns that value to the variable (variableReference).
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| Example |
var i : int
i := 24 % Variable i becomes 24
var a : array 1 .. 25 of string
a (i) := "Ralph" % The i-th element of a becomes "Ralph"
…
var b : array 1 .. 25 of string
b := a % Array b becomes (is assigned) array a
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| Details | The expression on the right of := must be assignable to the variable on the left. For example, in the above, any integer value, such as 24, is assignable to i, but a real value such as 3.14 would not be not assignable to i. Entire arrays, records and unions can be assigned. For example, in the above, array a is assigned to array b. See assignability for the exact rules of allowed assignments. You cannot assign a new value to a constant (const). There are short forms that allow you to write assignment statements more compactly. For example,
can be shortened to
In Turing, there are short forms for combining +, = and * with assignment. For example, i *= 2 doubles i. There are also short forms to allow any binary operator to be combined with assignment. For example, i shl= 2 shifts i by 2 to the left.
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