Chapter 3

Answers to Exam Preparation Exercises

3. Evaluating.expressions

(a) 3 (b) 4 (c) 37 (d) 22 (e) 23 (f) 100

4. A = 5 and B = 2 (Assumption: Writing an integer value with no fieldwidth specified defaults to a width of 1).

Statement Produces

Writeln('A = ', A:6, ' B = ', B:6); A = 5 B = 2

Writeln('Sum = ', A + B:6); Sum = 7

Writeln(A DIV B:6); 2

Writeln(B - A:6); -3

6. Write the assignment statement in algebraic notation.

7. Evaluate the expressions.

(a) 0.23529 (b) 2.25 (c) 44.2 (d) 5 (e) 0 (f) 21 (g) 2 (h) 5 (i) 1

8. Show the program's output. Underscore indicates blank:

AB

___413_is the value of X

2.1800000000E+01_is the value of Y

9. Evaluate the expressions:

(a) 9.1 (b) 7.0 (c) 27 (d) 6 (e) 5.0

10. a) 26 b) 'reparation' c) 1 d) 16 e) 16 f) 16.

12. The output from the statements (• indicates blank):

(a) •47810.59322

(b) 47810.5932

(c) ••47810.5932200

(d) 47810.6

(e) 0.031

(f) •••-0.031067

(g) -3.1E-02 (Equivalent to Y:7:-3)

Answers to Programming Warm-Up Exercises

3. This is a laboratory exercise for the student and requires no answer here.

4. This also is a laboratory exercise for the student, but it requires that changes be made to the program before it is entered. A sample is given here.

PROGRAM Two (Output);

(* Programming Assignment Two *)

(* William T. Verts *)

(* June 27, 1986 *)

(* This program computes the cost per ounce given total *)

(* cost and the weight expressed in pounds and ounces. *)

CONST

TCost = 600; (* Total cost *)

Pounds = 10; (* Weight in pounds *)

Ounces = 11; (* Additional weight in ounces *)

VAR

TotOz, (* Total weight in ounces *)

UCost: (* Computed cost per ounce *)

Real;

BEGIN

TotOz := 16 * Pounds;

TotOz := TotOz + Ounces;

UCost := TCost / TotOz;

Writeln('Cost per unit ', UCost)

END.

5. Complete the program:

PROGRAM Rectangle (Output);

(* This program finds the perimeter and the area of a rectangle *)

(* given the length and width *)

VAR

Length, (* Length of the rectangle *)

Width, (* Width of the rectangle *)

Perimeter, (* Perimeter of the rectangle *)

Area: (* Area of the rectangle *)

Real;

BEGIN (* Rectangle *)

Length := 10; (* Assigns a value to Length *)

Width := 5; (* Assigns a value to Width *)

Perimeter := Length * 2.0 + Width * 2.0; (* Computes perimeter *)

Area := Length * Width; (* Computes area *)

Write('The perimeter of a rectangle with length ',

Length:8:2, ' and width ', Width:8:2, ' is');

Writeln(Perimeter:8:2);

Writeln('and the area of the rectangle is ', Area:8:2)

END. (* Rectangle *)

6. Assignment statement:

Sum := N * (N + 1) DIV 2

8. Pascal fragment to output substring positions:

First := Pos('res', Sentence);

RestOfSentence := Copy(Sentence, First+3, Length(Sentence));

Position := Pos('res', RestOfSentence);

Second := First + 2 + Position;

RestOfSentence:=

Copy(RestOfSentence, Position+3, Length(RestofSentence));

Position := Pos('res', RestOfSentence);

Third := Second + 2 + Position;

Writeln('Second Occurence of res: ', Second, ' Third: ',Third);

9. Change exercise 8 to work with user-specified string.

First := Pos(Target, Sentence);

RestOfSentence := Copy(Sentence, First+3, Length(Sentence));

Position := Pos(Target, RestOfSentence);

Second := First + 2 + Position;

RestOfSentence :=

Copy(RestOfSentence, Position+3, Length(RestofSentence));

Position := Pos(Target, RestOfSentence);

Third := Second + 2 + Position;

Writeln('Second Occurence of ', Target, ': ', Second,

' Third: ', Third);