programming chapter 2 week 3

8/13/2019 Programming Chapter 2 Week 3

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FCS 0084 Programming Chapter 2

Operation and Expression Week 3

Management and Science University 1

Chapter 2

Operation and Expression


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Learn how C computes data

TOPICObjectives:

TOPIC Objectives:


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Symbol Meaning Example Result

+ Addition 2 + 3 5

- Subtraction 5 - 3 2* Multiplication 4 * 2 8

/ Division 10 / 2.0 5

% Modulus 5 % 2 1

2.1MathOperatorsandPrecedence

2.1 Math

Operators and Precedence

Primary Math OperatorsPrimary Math Operators


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Note:

If the modulus %sign is needed to be displayed as part of a text string, use

two, ie %%

#include

main()

{

intsum = 50;floatmodulus;

modulus = sum % 10;

printf("The %% of %d by 10 is %f\n", sum, modulus);

}

Sample Program OutputThe % of 50 by 10 is 0.000000

What does the following change do to the printed output of the previous program?

printf("The %% of %d by 10 is %.2f\n", sum, modulus);


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Example of expression:

Order of Precedence

First: { *, / , % }

Second: { +, - }

Order of PrecedenceOrder of Precedence

6 + 2 * 3 - 4 / 2

6 + 6 - 4 / 2

6 + 6 - 2

12 - 2

10

Also called math hierarchy Determine exactly how C computes formulas


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Used to override the order of precedence

Example of

expression:

Average = ( first + second ) / 2.0;

NOT

Average = first + second / 2.0;

ParenthesesParenthesesParentheses

2 * 3 + 4

6 + 4

10

2 * ( 3 + 4 )

2 * 7

14

Note: Sometimes parentheses is must exist in expression.

Example;An average of 2 numbers.


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Syntax:

var iableName = Expressio n;

Expression:

Can be constants,variableor combination of constants

and

variables using math operators

Examples of

assignments

statements:

Value = 7;

A = B;Y = 2 * X + 2;

Assignment StatementAssignment StatementsAssignment Statements

Refer: TOPIC 1 (1.5)


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Assign the same value to different variables

Three

assignments

statements:

A = 4;

B = 4;

C = 4;

A = B = C = 4;

What is the meaning ofA = B = C = D;

Multiple assignment form:

Multiple AssignmentMultiple AssignmentMultiple Assignments

Sets all counter variables to zero:

passed = 0;failed = 0;

index =0;total = 0;

passed=failed=index=total=0;


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Symbol Normal Compound

Assignment Assignment

+= A = A + 2; A += 2;

-= B = B - 3; B -= 3;

*= C = C * D; C *= D;

/= E = E / 2.5; E /= 2.5;

%= F = F % 4; F %= 4;

Compound AssignmentCompound AssignmentCompound Assignments

Convert this compound assignment to normal assignment

salary += (bonus + overtime - tax);

Combination of math operatorsand assignment


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Temporarily change a variables data typefrom its defined data type to a

new one when an expression have mixed data types

Conversion may occurautomatically or by typecasting.

Example of

assignment

statements:

/* Automatic Conversion */

int bonus= 150;

float total,salary= 900.45;

total =salary+ bonus;

/* Typecast */

total = salary + (float) bonus;

Syntax:

(data type) expression

Integer & Float

Float & Float

Typecast

TypecastTypecast


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Symbol Meaning

== Equal to

> Greater than

= Greater than or equal to


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Assume that a program initializes four variables:

int a=5,b=10,c=15,d=5;

The following expressionsare then TRUE:

1. a==d

2. b< c

3. c>a

4. b>=a

5. dc

3. d< a

4. d> a

5. a!=d

6. c


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2.3 Arithmetic Arithmetic calculations Use *for multiplication and /for division

Integer division truncates remainder

7/5evaluates to 1 Modulus operator(%) returns the remainder

7%5evaluates to 2


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Operator precedence

Some arithmetic operators act before others (i.e.,

multiplication before addition)

Use parenthesis when needed

Example: Find the average of three variables a, b

and c Do not use: a + b + c / 3 Use: (a + b + c ) / 3


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C opetrationArithmeticoperator

Algebraicexpression

C expression

Addition + f + 7 f + 7

Subtraction pc p - c

Multiplication * bm b * m

Division /or or

xx y x y

y x / y

Remainder % rmods r % s

Arithmetic operators.


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Common Programming Error An attempt to divide by zero is normally

undefined on computer systems and

generally results in a fatal error, i.e., anerror that causes the program to terminate

immediately without having successfully

performed its job. Nonfatal errors allowprograms to run to completion, often

producing incorrect results.


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Precedence of arithmetic

operators.

Operator(s) Operation(s) Order of evaluation (precedence)

( ) Parentheses Evaluated first. If the parentheses arenested, the expression in the innermost pair isevaluated first. If there are several pairs of

parentheses on the same level (i.e., not nested),they are evaluated left to right.

*/

%

MultiplicationDivisionRemainder

Evaluated second. If there are several, they areevaluated left to right.

+-

AdditionSubtraction

Evaluated last. If there are several, they areevaluated left to right.


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Order in which a second-degree

polynomial is evaluated.


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Good Programming Practice

Using redundant parentheses in

complex arithmetic expressions

can make the expressions clearer.


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2.4 Decision Making: Equality and

Relational Operators Executable statements

Perform actions (calculations, input/output of data)

Perform decisions May want to print "pass"or "fail"given the value of a test grade


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ifcontrol statement

Simple version in this section, more detail later If a condition is true, then the body of the if

statement executed

0is false, non-zero is true

Control always resumes after the ifstructure

Keywords

Special words reserved for C

Cannot be used as identifiers or variable names

programming chapter 2 week 3

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