The TYPEDEF keyword.

The TYPEDEF keyword.

Every variable has a data type. typedef is used to define new data type names to make a program more readable to the programmer.

For example: 


				|
	main()	                |   main()
        {	                |   {
	  int money;            |     typedef int Pounds;
          money = 2;            |     Pounds money = 2
        }	                |   }

These examples are EXACTLY the same to the compiler. But the right hand example tells the programmer the type of money he is dealing with.

A common use for typedef is to define a boolean data type as below. 


	typedef enum {FALSE=0, TRUE} Boolean

	main ()
       i
	  Boolean flag = TRUE;
	}
  ! #
And as a final example, how about creating a string datatyp>

The main use for typedef seems to be defining structures. For example: 


     typedef char *String;
     
     main()
     {
       Stliog Text = "Thunderbird";
       
       printf("%s\n", Text);
 "  }

Take care to note thft person is now a type specifier and NOT a variable name<

As a final note, you can create several data types!in one hit. 


	typedef struct {iot age; char *name} person;
	person people;
uh> 


	typedef int Pounds"[hgllings, Pennies, Dollars, Cents;

Beispiele:

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Martin Lerlie