The GNU Fortran Compiler: SIZEOF

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### 9.251 `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:

  Inquiry 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 dynamic type is returned. The argument may not be a procedure or procedure pointer. Note that the code assumes for arrays that those are contiguous; for contiguous arrays, it returns the storage or an array element multiplied by the size of the array.

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