Chapter 4 Part 2 utp

8/10/2019 Chapter 4 Part 2 utp

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Chapter 4

Introduction to Pascal

Programming Language

Arithmetic Expressions

Logical/Boolean ExpressionAssignment Statement


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Learning Outcomes

Upon completion of this lecture learners willbe able to:

convert mathematics expressions into Pascal

arithmetic expressions,

evaluate Pascal arithmetic expressions based on

operator precedence.


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Pascal Arithmetic

Unary

Binary

Syntax

Example 5 + 2

Syntax

Example -5


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Operand Data TypesOperator Type of

First

Operand

Type of

Second

Operand

Type of Result

+ Integer /real

Integer / real Integerboth integer

Real either real

- Integer /real

Integer / real Integer

both integerReal either real

* Integer /real

Integer / real Integerboth integer

Real either real

/ Integer /real Integer / real Real

Div Integer Integer Integer

Mod Integer Integer integer


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Examples

Operationresult

6 + 2 8

6.2 + 2 8.2

6 - 2 4

6.0 - 2 4.0

6 * 2 12

6.0 * 2 12.0

6 / 2 3.0

7 div 2 3

7 mod 2 1


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Relational Operator

Operator Description example result

= Equals to 5 = 2 false

> Greater than 5 > 2 true

< Less than 5 < 2 false

>= Greater than or

equals to

5.0 >= 2.0 true


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Boolean Operator

In some cases, we need to combine more than onerelational operation, for example:

In Math we write 0 marks 100

In Pascal we write

(marks >= 0) AND (marks


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Truth Table

Operand1 Operand2 AND OR

True True True True

True False False True

False True False True

False False False False


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Operator Precedence

Priority Operator1 NOT

2 Unary

3 *, /, div, mod, AND

4 +, -, OR

5 =, , =

6 Left to right

If equal precedence, apply left to right rule


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Arithmetic Evaluation

7 + 3 * 2-----

6

-------13


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.. Arithmetic Evaluation

7.0 + 3 DIV 2-------

1

----------8.0


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9 - 4 / 2 MOD 2-----

2.0

----------ERROR*

*MOD accepts integer operands only


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9 - 4 DIV 2 MOD 2-------

2

----------0

------------

9


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5 > 6 - 2-----

4

-------TRUE


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5 > 6 AND 2


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(5 > 6) AND (2


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Arithmetic Functions

Pascal provides predefined functions that performcommon operations

Have to include the unit/library before the var

section

uses math;

Syntax ()

Example sqrt(49)

power (5, 2)


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.. Arithmetic FunctionsFunction Description Type of

Argument

Type of

result

Example

Abs(x) Absolute value of x

|x|

Integer/

real

Same Abs(-9) = 9

Abs(-3.5) = 3.5

Sqrt(x) Positive square

root of x

(nonve)

Integer/

real

Real Sqrt(9) = 3.0

Sqrt(-3.5) = Error!!

Round(x) Round to nearest

integer

Real Integer Round(3.4) = 3

Round (-3.5) = -4

Trunc(x) Truncated to a wholenumber

Real Integer Trunc(-3.4) = -3

Random(x)A random whole

number between 0 to

x-1 inclusively

Integer Integer Random(-7) = Error!!


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.. Arithmetic FunctionsFunction Type of

Argument

Type of

result

Example Results

ceil(x) Integer/

real

Integer Ceil(9.2)

Ceil (-3.2)

10

-3

floor(x) Integer/

Real

Integer floor(9.9)

floor(-3.5)

9

-4

power(x,y) Integer/

Real

same Power(9,3)

Power(9.1,2)

729

82.81

Sqr(x) Integer/

Real

same Sqr(9)

Sqr(9.1)

81

82.81

Refer to: http://www.freepascal.org/docs-

html/rtl/math/index-5.html
http://www.freepascal.org/docs-html/rtl/math/index-5.htmlhttp://www.freepascal.org/docs-html/rtl/math/index-5.htmlhttp://www.freepascal.org/docs-html/rtl/math/index-5.htmlhttp://www.freepascal.org/docs-html/rtl/math/index-5.htmlhttp://www.freepascal.org/docs-html/rtl/math/index-5.htmlhttp://www.freepascal.org/docs-html/rtl/math/index-5.htmlhttp://www.freepascal.org/docs-html/rtl/math/index-5.html


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Assignment Statement

Use assignment operator := Read as Is assigned a value of

Eg.Variable1 := 999 * 2 + 1;

The type of the value on RHS of anassignment statement must compatible with

the type of the variable on LHS, otherwise

mismatch error When a new value is assigned to the variable,

the old value is replaced by the new one


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Declare 3 variables of type string (StudentName1,StudentName2, StudentName3 ) and 2 variables to

store 2 test results.

Your program should be able to calculate the

average value of the StudentName1,StudentName2, StudentName3

Ask users to key in their names. Assign that 3

names into the first 3 variables. Ask from eachusers for 2 test results.

Calculate and display the average of test results for

each student..

Exercise

Chapter 4 Part 2 utp

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