C++ operator ','

Question

Possible Duplicate:
C++ Comma Operator

what is result of operator ',' by standard? Last argument? in code like this, for example:

int a = 0;
int b = 1;

while(a,b);

or using it like this is not allowed? MSVS thiks that result is b, is it true?

sorry for duplicating, did not know how this operator called in english )

Duplicate of http://stackoverflow.com/questions/54142/c-comma-operator — Andreas Rejbrand, Jun 15 '10 at 21:02

score 8 · Accepted Answer · answered Jun 15 '10 at 21:01

8

The sequence of statements is executed and the return value is the evaluation of the final statement.

answered Jun 15 '10 at 21:01

Amardeep AC9MF

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Is it a statement or an expression? – Martin York Jun 15 '10 at 21:28

score 7 · Answer 2 · answered Jun 15 '10 at 21:02

7

The comma operator always returns its last argument, unless the operator is overloaded.

answered Jun 15 '10 at 21:02

zildjohn01

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+1 for mentioning "unless overloaded" – Steve Folly Jun 15 '10 at 21:50

score 3 · Answer 3 · answered Jun 15 '10 at 21:02

3

The result of the ',' operator is the last evaluated expression, yes.

answered Jun 15 '10 at 21:02

Remy Lebeau

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score 1 · Answer 4 · answered Jun 15 '10 at 21:04

The result of , operator is its right-hand operand, i.e. the subexpression that follows ,.

Operator , is left-associative, meaning that if you have a chain of several , operators with operands and no braces, then the last subexpression in the chain is the result.

C++ operator ','

4 Answers4