SIZEOF - The GNU Fortran Compiler
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### 8.228 `SIZEOF` — Size in bytes of an expression

Description:
  `SIZEOF(X)` calculates the number of bytes of storage the expression `X` occupies.
Standard:
  GNU extension
Class:
  Intrinsic function
Syntax:
  `N = SIZEOF(X)`
Arguments:

  X | The argument shall be of any type, rank or shape.

Return value:
  The return value is of type integer and of the system-dependent kind C_SIZE_T (from the ISO_C_BINDING module). Its value is the number of bytes occupied by the argument. If the argument has the `POINTER` attribute, the number of bytes of the storage area pointed to is returned. If the argument is of a derived type with `POINTER` or `ALLOCATABLE` components, the return value does not account for the sizes of the data pointed to by these components. If the argument is polymorphic, the size according to the declared type is returned. The argument may not be a procedure or procedure pointer.
Example:

                   integer :: i
                   real :: r, s(5)
                   print *, (sizeof(s)/sizeof(r) == 5)
                   end

  The example will print `.TRUE.` unless you are using a platform where default `REAL` variables are unusually padded.

See also:
  C_SIZEOF, STORAGE_SIZE