| Functions & Pointer |
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| Statement functions |
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| It is defined in a program or a subprogram and it is used internally
where it defined. It has a single statement and similar in form
to an arithmetic, logical or character assignment statement. In
a statement function statement must appear only after the specification
statements and before the first executable statement of the program
unit in which it is referenced. |
| The general form of statement function is: |
| fun (list) = e |
| where fun is user defined name of the function; |
List is the variable names which are the arguments of the function
and must be separated by comma; Arguments of the function may
be dummy or actual. |
| e is an expression which must be one of the given below: |
· A constant
· A variable
· An array element reference
· An intrinsic function reference
· A reference to a statement function for which the statement
function statement appears in preceding
· lines of the program unit
· An external function reference
· A dummy procedure reference
· An expression enclosed in parentheses that meets all
of the requirements specified for the expression e
· Arguments of the function may be dummy or actual. |
| Example: |
| FUND (Y) = Y * Y + 2.2 |
| Here FUND is user defined name of the function ie. statement function
name. Y is the variable names which are the arguments of the function
which is enclosed in between (). This statement function is of
real type. Its expression can be written as Y *Y + 2.2 |
| Restrictions |
| A statement function must appear after the specification statements
and before the first executable statement of the program unit
in which it is referenced. |
| A statement function is not executed at the point where it is
specified. |
| The actual argument must agree in order, number and type with
corresponding dummy arguments. |
| A dummy argument cannot be an array or function name. The same
argument cannot be specified more than once in the argument list.
A statement function cannot be invoked recursively. |
| Example of arithmetic statement function: |
PARAMETER ( PI=3.14159)
REAL RADIUS, VOLUME
SPHERE (R) = 4.0 * (R**3)/ 3.0
READ*,RADIUS
VOLUME = SPHERE( RADIUS) |
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