CS 171 Sample Test 2

(8 pts) Describe the output produced by the following code:
```
Count := 1;
WHILE Count < 10 DO
   WRITELN (Count)
```

(8 pts) What is the output produced by the following code?

Exp := 0;
Base := 3;
Power := 1;
WHILE Exp < 5 DO
   BEGIN
      Power := Power * Base;
      Exp := Exp + 1;
      WRITELN (Power)
   END

(12 pts) Write a Pascal program (omit comments) that asks for the user to input their name, and then greets them, as in
```
What is your name? Jack
Hello, Jack!
What is your name?
```
As the example shows, the program continues to ask for names and greet users. However, when your name is typed in, the program responds with
```
What is thy bidding, O my Master?
```
and then ends.

(8 pts) What is the output produced by the following code?

Count := 1;
Total := 0;
REPEAT
   Count := Count + 1;
   Total := Total + Count;
   WRITE (Total)
UNTIL Count = 10;
WRITELN (Total)

(8 pts) Rewrite the following program using the style rules:

program power ; var base , exponent, count : integer ; results : real;
begin write ('Enter base for power: ') ; readln (base) ;
write ('Enter exponent for power: ') ; readln (exponent) ; Results := 1;
Count:=0;
repeat results := results * base ; count := count + 1 until
count >= exponent ; write ('Power is: '); writeln (results : 1 : 1) end.

(8 pts) Write a REPEAT-UNTIL loop that asks the user to input a number, repeatedly, until a positive number is entered.

(8 pts) What is wrong with the following?

FOR Count := 1 TO Finish DO
   IF Finish > 4
      THEN Count := Finish
      ELSE WRITE (Count)

(8 pts) What is the output produced by the following code?

FOR Outer := 1 TO 6 DO
   FOR Inner := 5 DOWNTO 1 DO
      IF Inner <> Outer
         THEN WRITE (Inner)

(8 pts) The value 5 factorial (written 5! in mathematics) is the product 5*4*3*2*1. Similarly, to calculate N factorial, we would multiply N*(N-1)*...*2*1, as in the following:
```
Fact := 1;
FOR I := N DOWNTO 1 DO
   Fact := Fact * I
```
Write a procedure Factorial(N,Result) that would calculate N factorial and return the answer in Result.
(8 pts)Write a function Factorial(N) that calculates N factorial.
(8 pts)Discuss which approach, procedure or function, is the most appropriate for calculating factorials.
(8 pts)Discuss the difference between Value and Variable parameters. Explain when to use each.