C++ Syntax: Assignment: = op=
Description
The assignment operator, as in FORTRAN, takes the value of the expression on the
right hand side and stores it in the variable on the left hand side. For example:-
<![CDATA[
sum = sum + count;
]]>
The above construction is so common that C++ has a shortcut for it:-
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sum += count;
]]>
and the same idea works for any binary operator e.g.:-
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weight *= scale;
]]>
i.e. by following a binary operator directly by an =.
Unlike FORTRAN, the assignment operator, like all other C++
operators, returns a value (its the value of the right hand side).
This means that the assignment is itself just a value that can be assigned
so that:-
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a = ( b = 0);
]]>
sets both a and b to zero. The above brackets are unnecessary:-
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a = b = 0;
]]>
is the same as the order in which assignment operators work is
right to left (so a gets a 0 not what was in b before it got a zero).
See operator
precedence
Other Uses for = op=
None.
Usage Notes
Be careful not to confuse = with
==
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Nick West