Topic I Solutions

Solutions TOPIC I: VAL & VAR

Exercises :

(D1) VAR-demo

(S1)

(S2)

(S3)

(X1)

(H1)

(H2)

(T1)

D1: VAR-demo.

MODULE D1;
<* NOOPTIMIZE + *>
FROM IO IMPORT RdChar, WrChar, WrStr, RdStr, WrLn, RdCard, WrCard, RdInt, WrInt, RdReal, WrReal, RdBool, WrBool;
FROM RealMath IMPORT sqrt, exp, sin, cos, tan, arcsin, arccos, arctan, power, round;

    PROCEDURE Do(VAR x: CARDINAL; y: CARDINAL); (* Note the VAR parameters *)
                                                (* change x & y between VAL & VAR *)
    BEGIN
      x := 10; (* we change values of x & y *)
      y := 7;
    END Do;

VAR
a, b: CARDINAL; (* variable-declarations *)

BEGIN
    WrLn;
    (* a & b get initiial values *)
    a := 1;
    b := 2;
    WrStr("Values BEFORE Do procedure:");WrLn;
    WrStr(" a = ");WrCard(a, 0);WrLn;
    WrStr(" b = ");WrCard(b, 0);WrLn;

Do(a, b);

    WrStr("Values AFTER Do procedure:");WrLn;
    WrStr(" a = ");WrCard(a, 0);WrLn;
    WrStr(" b = ");WrCard(b, 0);WrLn;

END D1.

run the procedure to see if your calculated result is correct
add writes of x1, x2 & x3 to see intermediate results

Solutions TOPIC I: VAL & VAR

Contents :

Exercises :

D1: VAR-demo.

S1

S2

S3

X1

H1

H2

T1