ANSI C Type Qualifiers

You've seen that a variable is characterized by both its type and its storage class. ANSI C adds two more properties: constancy and volatility. These properties are declared with the keywords const and volatile, which create qualified types. The C9X committee proposes adding a third qualifier, restrict, designed to facilitate compiler optimizations; Appendix H, "The C9X Committee," discusses it briefly.

The const Type Qualifier

Chapter 4, "Character Strings and Formatted Input/Output," and Chapter 10 have already introduced const. To review, the const keyword in a declaration establishes a variable whose value cannot be modified by assignment or by incrementing or decrementing. On an ANSI-compliant compiler, the code

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