HP C/iX Reference Manual (31506-90011)

70 Chapter5
Expressions
The sizeof Operator
The sizeof Operator
The sizeof operator is used to determine the size (in bytes) of a data object or a type.
Syntax
sizeof unary-expression
sizeof ( type-name )
Description
The result of the sizeof operator is an unsigned int constant expression equal to the
size of its operand in bytes. You can use the sizeof operator in two different ways. First,
you can apply the sizeof operator to an expression. The result is the number of bytes
required to store the data object resulting from the expression. Second, it may be followed
by a type name inside parentheses. The result then is the number of bytes required to
store the specified type.
In either usage, the sizeof operator is a compile-time operator that you can use in place of
an integer constant.
The usual conversion of arrays of T to pointers to T is inhibited by the sizeof operator.
The sizeof operator returns the number of bytes in an array rather than the number of
bytes in a pointer.
When you apply the sizeof operator to an expression, the expression is not compiled into
executable code. This means that side effects resulting from expression evaluation do not
take place.