Declarations

Overview

C declarations were designed so that the declaration of an object looks like the use of the object. This isn’t quite true - keywords like volatile and const only exist in declarations - but for the most part, this philosophy can be leveraged to read C declarations.

Declarators

A declarator in C is roughly an identifier along with pointers, function brackets, or array indications. Pointers will look like one of:

• *
• * const
• * volatile
• * const volatile
• * volatile const

whereas direct declarators will look like one of:

• identifier
• identifier[size]
• identifier(args)
• (declarator)

Declarations

A declaration consists of at least one type-specifier (e.g. signed short), storage class (e.g. static), and/or type qualifier (e.g. const) as well as one or more declarators.

Declarations can be read by complying with the precedence rules outlined below:

1. Find the name of the declaration.
2. Obey the following precedence rules:
   1. Parentheses grouping together parts of a declaration
   2. Postfix operators () and []
   3. Prefix operator: the asterisk * denoting “pointer to”
3. If const and/or volatile keyword is next to a type specifier, it applies to the type specifier. Otherwise it applies to the pointer asterisk on its immediate left.

Bibliography

• Bryant, Randal E., and David O’Hallaron. Computer Systems: A Programmer’s Perspective. Third edition, Global edition. Always Learning. Pearson, 2016.
• “ISO: Programming Languages - C,” April 12, 2011, https://port70.net/~nsz/c/c11/n1570.pdf.
• Van der Linden, Peter. Expert C Programming: Deep C Secrets. Programming Languages / C. Mountain View, Cal.: SunSoft Pr, 1994.