Operator precedence table for the C programming language

2
votes

What would a correct operator precedence table that lists all operators in the C language look like?

I have made extensive searches on the web, and found many such precedence tables. Alas, I haven't found a single one filling these requirements:

  • Lists all operators in the C language as defined in ISO 9899:2011, without mixing in any C++ operators.
  • Lists the operators in the complete and correct priority order.
3
coperator-precedencec11
Operator precedence in C is specified by the order the various operator groups appear in the standard (chapter 6.5). This is tedious reading, a "precedence table" that quickly sums up all operators would be preferable, particularly as reference for programming discussions on SO. If we could make such a post and use as a C FAQ, that would be great. – Lundin
possible duplicate of Precedence between member access from a pointer and cast – jxh
@Lundin: Actually, operator precedence in specified in C by the grammar. The order they appear in the standard is informative, not normative. – Eric Postpischil
@Lundin: That is consistent with what I wrote. – Eric Postpischil
An operator precedence table wouldn't have any explaining text either. – jxh

3 Answers

6
votes

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Explanation

Prec. denotes operator precedence, where group 1 has the highest precedence and group 17 the lowest.

Assoc. denotes operator associativity, where such is applicable. Associativity can be either left-to-right or right-to-left.

Sources

My ambition with this post is to provide a operator precedence table on-site at Stack Overflow, which is correct and canonical. This operator precedence table corresponds directly to chapter 6.5 of ISO 9899:2011, where we can read (6.5/3):

The grouping of operators and operands is indicated by the syntax. 85)

And then as a comment, in the informative (not normative) foot note:

85) The syntax specifies the precedence of operators in the evaluation of an expression, which is the same as the order of the major subclauses of this subclause, highest precedence first. /--/

Within each major subclause, the operators have the same precedence. Left- or right-associativity is indicated in each subclause by the syntax for the expressions discussed therein.

All formal operator names from the table are taken from chapter 6.5, where such a name could be found in normative text. Informal names were included in the cases where the programmer community might be more familiar with another name than the one given in the standard.

1
votes

Here:

http://basen.oru.se/c/operators.html

(I added _Alignof, which I think is the only new operator in C11, to my own table, and published it there. Maybe that's cheating? Comments and suggestions on how to improve the table are welcome.)