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The comma operator is a binary operator
whose operands are expressions. The expression operands are evaluated
from left to right. Syntax | |
expression ::=
assignment-expression
expression , assignment-expression |
Description | |
The comma operator is a "no-operation" operator. Its left
operand is evaluated for its side effects only. Its value is discarded.
The right operand is then evaluated and the result of the expression
is the value of the right operand. Because the comma is a punctuator in lists of function arguments,
you need to use care within argument lists to ensure that the comma
is treated as a comma operator and not as an argument separator. This example passes three arguments to f().
The first is the value of a,
the second is the value of b
which is set equal to 7 before the function call, and the third
is the value of c.
The comma separating the assignment expression and the argument
b is enclosed
in parentheses. It is therefore interpreted as a comma operator
and not as an argument separator. Examples | |
func(a, (b=0, b), c) /*Set b to 0 before passing it to func. */
index++, a = index /*Increment index and then assign it to a.*/
i=0, j=0, k=0 /*Initialize i,j,k to 0 */ |
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