Structure Summary

What is a structure:

· Data type you create with parts

· Can contain an array / Can be contained by an array

· Passes by value unless explicitly by pointer

Defining a struct:

· struct workerstuff { int rate, hours, gross;} ;

· Use Typedef

o just the tag: typedef struct workerstuff Worker;

o the entire structure typedef struct { int rate, hours, gross;} Worker ;

Declaration

· single struct variable

o option 1 with combined def : struct workerstuff { int rate, hours, gross;} worker;

o option 2 referencing earlier definition: struct workerstuff worker;

o If typedef used: Worker worker;

· Array of a structure

o struct workerstuff workerArr[];

· Pointer to a structure

o struct workerstuff * workerPtr;

Access variable:

· single struct variable – dot : worker.rate;

· Array of a structure - Access via dot and subscript: WorkerArr[1].rate

· Pointer to a structure - Access via arrow : workerPtr->rate or (*workerPtr).rate

Union

· Definition by choices, not parts

· Takes on the size of the largest possible choice

· Definition: union number {int x; int * p;};

· Declaration and use have the same syntax as structure.

Enum:

· Naming constants, integer underlies it

· Use it to create a variable with only those possible choices

· Definition: enum days { SUN, MON, TUE, WED, THUR, FRI, SAT};

· Declaration: enum days day;

· Use: day = SUN;

Good Tutorials: