CSci 3102 Extension
Winter 1994

				Exercises - 1
				-------------

1. Which of the following are legal Pascal identifiers?

	a) NigHt	b) 3Mxyz	c) X-Ray	d) p1234
	e) count/4	f) 32.76	g) to day	h) begin
	i) read		j) File_Manager

2. Classify each of the following as an integer constant, real constant
   or  neither :

	a) +1		b) -(-1)	c) five		d) 1.2x10
	e) 24E0		f) 1,024	g) .3E2		h) 5E0.5
	i) 5E-5		j) 3E 10

3. Which of the following are legal string constants?

	a) '$19.25'	b) 'Don't'	c) 'Doesn''t'	d) 'too late'
	e) '12 + 34'	f) '(2e10)'	g) ''hello''    h) ''''

4. Find the value of the following expressions, or explain why it is
   not a valid expression :

	a) (2+3)(4+5)			b) 2*-3+4
	c) 2 DIV 3 + 3 / 5		d) 9 DIV (3 + 1) * 4
	e) 7 + 7 MOD 3			f) 9 / 2 DIV 3	
	g) 7 MOD (5 MOD 3) 		h) 25 * 1 DIV 2
	i) trunc (8 / 5) + round (8 /5)


5. Write a CONSTANT section to associate each of the following identifers
   with its respective constant value.

	Identifier	Constant Value
	----------	--------------
	
	month 		july
	fica		123-45-6789
	price		$95.00
	gross		2500.00
	partno		48874
	bound		0.0039

6. Write a declaration that will associate each of the following identifiers
   with its respective data type.

	Identifier	Data Type
	----------	---------

	period 		char
	terminal	boolean
	status		char
	index		integer
	row		integer


7. Assuming that Number is of integer type, xValue and yValue are
   of real type, Grade is of character type, and Found is of boolean
   type, determine which of the following are valid Pascal statements.

	a) xValue = 2.738	b) xValue := 2.0E3
	c) Grade := 'B+'	d) yValue := 1
	e) xValue := '1.0'	f) Number + 1 := Number
	g) xValue := Number	h) Found := 'true'
	i) Grade := A		j) Number := yValue
	k) xValue : = 1.03

8. Write Pascal assignment statements for the following :

	a) X is incremented by DeltaX.
	b) Add the rightmost digit of Number to Number.
	c) Assign the last three digits of Stock with a decimal point
	   before the last two digits to Price (e.g if Stock = 1758316
	   then Price is assigned 3.16)

9. For each of the following tell whether the two expressions are equal :
   a , b, and c are integers.

	a) a * (b / c)   and  a * b / c
	b) a * (b DIV c) and  a * b DIV c
	c) a DIV b       and  a * (1 / b)
	d) (a + b) DIV c and  a DIV c + b DIV c

10. Assuming A,B, and C are integer variables and X,Y, and Z are real
    variables, tell what value, if any, will be assigned to each of the 
    variables, or expalin why an error occurs.

	a) readln(A, B, C);		Input : 1  2
	   readln(X, Y, Z);			3  4
						5  6

	b) read(A , X)			Input : 1  2.2
	   read(B , Y)				3  4.4
	   read(C , Z)				5  6.6

	c) readln(A);			Input : 1  2  3
	   read(B , C);				4  5  6.6
	   readln(X , Y);			7.9   8.9
	   read(Z);


11. Use truth tables to display the values of the following boolean
    expressions for all possible values of a, b, and c.

	a) NOT (a AND b)	b) (NOT a) OR (NOT b)
	c) a AND (b OR c)	d) (a AND b) OR (a AND c)

12. Write boolean expressions to express the following.

	a) y is strictly between 2 and 5.
	b) Alpha and Beta have the same sign.
	c) x is less than 3 or y is less than 4, but not both
	d) The boolean expression is TRUE if and only if x is TRUE and
           exactly one of y and z is TRUE.

13. Write a sequence of Pascal statements to 'swap' (interchange) the 
    values of two variables say x and y.