Page 144 - Standard Handbook Of Petroleum & Natural Gas Engineering

Computer Applications 129

WRITE(filename, a,b,c,d);
can then write four items to the file.
RESET(fi1ename);-Prepares a file for reading, beginning with the first item
in the file, and
READ(filename,X);
can then read the first item from the file.
Control statements-Affect the flow of statement execution within a program
unit (see subprogram statements below for passing of control between units).
The only general control statement in Pascal (which is rarely needed) is:
GOT0 line number;-Shifts control to the statement beginning at the
specified line number.

Conditional statements may be nested with other conditional statements and/
or with iterative statements. They are:

IF boolean statement THEN statement-Where statement may be a simple or
a compound statement (for boolean and relational operators, see Table 1-29)
and

IF boolean statement
THEN statement 1
ELSE statement 2-where the statements are as defined above

For example,
IF (PRSSR < MINP) OR (PRSSR MAXP) THEN
BEGIN
X(P1PENUM: = PREVX;
CORRPR( PRSSR,X( PIPENUM),AVT)
END
ELSE
PREVX: = X(IP);

and
CASE selector expression OF
label: statement;
label: statement;
...
label: statement
END
where, when the selector expression is evaluated, producing an ordinal value,
the statement following the label value which matches the selector expression
is executed, e.g.,
CASE PIPENUM OF
1: PREV: = FALSE;
MAXP: NEXT = FALSE
END: