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. */ main() { printf("%d \n", sizeof(int)); }

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

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

Finally, sizeof will return the length of a variable.

main() { 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.

Examples:

Example 2 Data objects.

See also:

Other operators

malloc function.