TOPS-20 PASCAL Language Manual - Bitsavers

PROCEDURES AND FUNCTIONS
label section
declares local labels.
constant section
defines local constant identifiers.
type section
defines local types.
variable section
declares local variables.
procedure-and-function section
statement
declares local procedures and functions.
specifies an action to be performed by the function. A function
can contain any of the statements oescribed in Chapter 5. A
function must contain a statement that assigns a value to the
function ioentifier (for every potential path through the code).
If it does not, the value of the function could be undefined.
A function consists of a heading and a block. The formal parameter
list in the function heading is identical in format to the list in the
procedure heading. The function block is similar in structure and
contents to the main program, with the following exceptions:
• The function cannot contain a value initialization section .
• The function block ends with END followed by a semicolon (;),
rather than a period (.) as in the main program. The
function does not have a block if it is a forward
declaration, or if it is defined externally (EXTERN(AL) or
FORTRAN) •
You must declare all variables that are local to the function, but you
should not redeclare a variable, type, or constant with the same name
as a formal parameter or the function identifier.
Each function must include a statement or statements that assigns a
value of the result type to the function name. The last value that is
assigned to the function name is returned to the calling program unit.
To use the value, include a function call in the calling unit. Unlike
a procedure call, a function call is not a statement. It simply
represents a value of the function's resuJt type.
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