Class 15: Compound and User-Defined Types in C

Held: Wednesday, 12 February 2003

Summary: Today we consider a number of structured types in C. We also consider typedef, C's primary mechanism for naming types.

Related Pages:

• EBoard.
• Lab on Structs and Other User-Defined Types.

Assignments:

• Read appendix B.3 of K& R.
• Scan the manual pages for those string procedures.

Notes:

• Almost immediately following today's class, select math faculty will be discussing summer research opportunities in Mathematics.
• Are there questions about the material from yesterday's or Monday's class?

Overview:

• Structures.
• Unions.
• Naming Types.
• Lab.

Structs

• Combine multiple variables into a unit.
• Why bother?
• Syntax

  struct name {
    field-declaration-1;
    ...
    field-declaration-n;
  };
  

• Variables then have type struct name.
• Use dot notation to get elements.
  • Life gets more fun when you learn pointers.

Unions

• Combine multiple variables into a unit.
• Assumed: Only one variable is active at one time.
• Otherwise, look similar to structs.

Typedefs

• Allows you to assign simpler (and multiple) names to types.
• Standard format:

  typedef type-name alternate-name;
  

• Why bother?

Lab

• Do the lab.
• Be prepared to reflect.