Mikroelektronika MIKROE-724 データシート
mikroBasic PRO for dsPIC30/33 and PIC24
MikroElektronika
223
Sizeof Operator
The prefix unary operator
sizeof
returns an integer constant that represents the size of memory space (in bytes) used
by its operand (determined by its type, with some exceptions).
The operator
sizeof
can take either a type identifier or an unary expression as an operand. You cannot use
sizeof
with expressions of function type, incomplete types, parenthesized names of such types, or with lvalue that designates
a bit field object.
Sizeof Applied to Expression
If applied to expression, the size of an operand is determined without evaluating the expression (and therefore without
side effects). The result of the operation will be the size of the type of the expression’s result.
Sizeof Applied to Type
If applied to a type identifier,
sizeof
returns the size of the specified type. The unit for type size is
sizeof(byte)
which is equivalent to one byte.
Thus:
sizeof(byte) ‘ returns 1
sizeof(integer) ‘ returns 2
sizeof(longword) ‘ returns 4
sizeof(float) ‘ returns 4
When the operand is a non-parameter of array type, the result is the total number of bytes in the array (in other words,
an array name is not converted to a pointer type):
dim i, j as integer
samples as integer[7]
...
j = sizeof(samples[1]) ‘ j = sizeof(integer) = 2
i = sizeof(samples) ‘ i = 10*sizeof(integer) = 20
If the operand is a parameter declared as array type or function type,
sizeof
gives the size of the pointer. When
applied to structures,
sizeof
gives the total number of bytes, including any padding. The operator
sizeof
cannot be
applied to a function.