The sizeof operator

sizeof will return the number of bytes reserved for a variable or data type.

The following code shows sizeof returning the length of a data type.

        /* How big is an int? expect an answer of 4. */
	   printf("%d \n", sizeof(int));

sizeof will also return the number of bytes reserved for a structure.

        /* Will print 8 on most machines. */
	    int a;
	    int b;
	  } TwoInts;
	printf("%d \n", sizeof(TwoInts));

Finally, sizeof will return the length of a variable.

	  char String[20];
	  printf ("%d \n", sizeof String);
 	  printf ("%d \n", sizeof (String));

In the example above I have printed the size of 'String' twice. This is to show that when dealing with variables, the brackets are optional. I recommend that you always place the brackets around the sizeof argument.


Example 1 Data types.

Example 2 Data objects.

See also:

The strlen function.

Other operators

malloc function.

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Martin Leslie