Intel® Fortran Compiler 16.0 User and Reference Guide
A reference to a component of a derived-type structure takes the following form:
parent [%component [(s-list)]] ... %component [(s-list)]
parent |
Is the name of a scalar or array of derived type. The percent sign (%) is called a component selector. |
component |
Is the name of a component of the immediately preceding parent or component. |
s-list |
Is a list of one or more subscripts. If the list contains subscript triplets or vector subscripts, the reference is to an array section. Each subscript must be a scalar integer (or other numeric) expression with a value that is within the bounds of its dimension. The number of subscripts in any s-list must equal the rank of the immediately preceding parent or component. |
Each parent or component (except the rightmost) must be of derived type.
The parent or one of the components can have nonzero rank (be an array). Any component to the right of a parent or component of nonzero rank must not have the POINTER attribute.
The rank of the structure component is the rank of the part (parent or component) with nonzero rank (if any); otherwise, the rank is zero. The type and type parameters (if any) of a structure component are those of the rightmost part name.
The structure component must not be referenced or defined before the declaration of the parent object.
If the parent object has the INTENT, TARGET, or PARAMETER attribute, the structure component also has the attribute.
The following example shows a derived-type definition with two components:
TYPE EMPLOYEE
INTEGER ID
CHARACTER(LEN=40) NAME
END TYPE EMPLOYEE
The following shows how to declare CONTRACT to be of type EMPLOYEE:
TYPE(EMPLOYEE) :: CONTRACT
Note that both examples started with the keyword TYPE. The first (initial) statement of a derived-type definition is called a derived-type statement, while the statement that declares a derived-type object is called a TYPE statement.
The following example shows how to reference component ID of parent structure CONTRACT:
CONTRACT%ID
The following example shows a derived type with a component that is a previously defined type:
TYPE DOT
REAL X, Y
END TYPE DOT
....
TYPE SCREEN
TYPE(DOT) C, D
END TYPE SCREEN
The following declares a variable of type SCREEN:
TYPE(SCREEN) M
Variable M has components M%C and M%D (both of type DOT); M%C has components M%C%X and M%C%Y of type REAL.
The following example shows a derived type with a component that is an array:
TYPE CAR_INFO
INTEGER YEAR
CHARACTER(LEN=15), DIMENSION(10) :: MAKER
CHARACTER(LEN=10) MODEL, BODY_TYPE*8
REAL PRICE
END TYPE
...
TYPE(CAR_INFO) MY_CAR
Note that MODEL has a character length of 10, but BODY_TYPE has a character length of 8. You can assign a value to a component of a structure; for example:
MY_CAR%YEAR = 1985
The following shows an array structure component:
MY_CAR%MAKER
In the preceding example, if a subscript list (or substring) was appended to MAKER, the reference would not be to an array structure component, but to an array element or section.
Consider the following:
MY_CAR%MAKER(2) (4:10)
In this case, the component is substring 4 to 10 of the second element of array MAKER.
Consider the following:
TYPE CHARGE
INTEGER PARTS(40)
REAL LABOR
REAL MILEAGE
END TYPE CHARGE
TYPE(CHARGE) MONTH
TYPE(CHARGE) YEAR(12)
Some valid array references for this type follow:
MONTH%PARTS(I) ! An array element MONTH%PARTS(I:K) ! An array section YEAR(I)%PARTS ! An array structure component (a whole array) YEAR(J)%PARTS(I) ! An array element YEAR(J)%PARTS(I:K) ! An array section YEAR(J:K)%PARTS(I) ! An array section YEAR%PARTS(I) ! An array section
The following example shows a derived type with a pointer component that is of the type being defined:
TYPE NUMBER
INTEGER NUM
TYPE(NUMBER), POINTER :: START_NUM => NULL( )
TYPE(NUMBER), POINTER :: NEXT_NUM => NULL( )
END TYPE
A type such as this can be used to construct linked lists of objects of type NUMBER. Note that the pointers are given the default initialization status of disassociated.
The following example shows a private type:
TYPE, PRIVATE :: SYMBOL
LOGICAL TEST
CHARACTER(LEN=50) EXPLANATION
END TYPE SYMBOL
This type is private to the module. The module can be used by another scoping unit, but type SYMBOL is not available.