Page 140 - Standard Handbook Of Petroleum & Natural Gas Engineering

Computer Applications 125

Pointer-Each value of a variable declared to be of a pointer type gives the
memory location of the element to which it points.
Statements. A Pascal statement may be shorter than or may continue over more
than one line, since a semi-colon separates statements. Reserved words are not
separated from statements; therefore the statement preceding the word END (see
later sections) requires no punctuation. END of the main program unit is
followed by a period. Comment lines are included in the program by placing
them between the symbols (* and *). Statements may be simple (single) or
compound, i.e., a series of simple statements joined together in a block which
is introduced by BEGIN and completed by END.

Nonexecutable Statements
Program unit heading-Program, procedure, or function name; the forms are:
PROGRAM name (input file name(s), output file name(s));

whete one input and one output file name, designated as INPUT and OUTPUT,
are assigned to default devices. For example,

PROGRAM TEST(INPUT,OUTPUT);
PROGRAM EDITOR(EDFILE, INPUT,OUTPUT);
and

FUN(:TION name(parameter list:type, . . .):function type;
PROCEDURE name(parameter list:type, . . .);
The declaration \:4R preceding a variable name(s) in a parameter list allows
the sub-program to modify the value of the variable stored in memory; if there
is no VAR preceding a variable name, the sub-program is passed only the value
of the parameter at the time of calling and cannot modify the stored value of
that variable in the calling unit, e.g.,
PROCEDURE SAMPLE(X:REAL; YCHAR);
PROCEDURE LOOP(VAR A,B,C:INTEGER; YCHAR);
FUNCTION CHECK(VAR NUM:REAL; VAR PNR:INTEGER):REAL;
FUNCTION BOUND(TEMP:REAL):BOOLEAN;
In standard Pascal, although only in a few implementations of the language, a
function or procedure name may also be a parameter to a sub-program. The
constants, types, and variables used in a sub-program, as well as those in the
main program, must be declared (see following declarations).
Label declaration-Labels identify an executable statement which may then
be referenced by GOTO; they may be 1-4 digits and must be declared by

LABEI, unsigned integer(s);
For example,

LABEL 50,999;