topic 2 student copy
Post on 06-Apr-2018
228 Views
Preview:
TRANSCRIPT
-
8/3/2019 Topic 2 Student Copy
1/46
Prepared by: Saltihie Bin Zeni
Jabatan Kej. Elektrik, PMU3 2 1 Start
-
8/3/2019 Topic 2 Student Copy
2/46
OVERVIEW
2.1
Understand constant andvariables
2.2
2.3
Understand operator andexpression
-
8/3/2019 Topic 2 Student Copy
3/46
2.1 Understand constant and variable
Constant
Values that do not change during program execution. Example : conts double PI = 3.14159 // conts is a
reserved word
Variables Variables are like small blackboards
We can write a number on them
We can change the number We can erase the number
Example: int answer;
-
8/3/2019 Topic 2 Student Copy
4/46
Identifiers Identifiers
Variables names are called identifiers Choosing variable names
Use meaningful names that represent data to
be stored
First character must be a letter
the underscore character
Remaining characters must be
letters
numbers
underscore character
-
8/3/2019 Topic 2 Student Copy
5/46
Example of identifiers
Identifier Valid Reason if Invalid
TotalSales Yes
_
Total.sales No Cannot contains .
4Qthrsales No Cannot begin with
numberTotal_sales$ No Cannot contain $
-
8/3/2019 Topic 2 Student Copy
6/46
Keyword Keywords (also called reserved words)
Are used by the C++ language
Must be used as they are defined in the
Cannot be used as identifiers
Examples of keyword:
asm class do auto conts break char huge while else case float if far
-
8/3/2019 Topic 2 Student Copy
7/46
Variables declaration (1) Before use, variables must be declared
Tells the compiler the type of data to store
Examples: int number_of_bars;
_ , _
int is an abbreviation for integer.
could store 3, 102, 3211, -456, etc.
number_of_bars is of type integer
double represents numbers with a fractionalcomponent
could store 1.34, 4.0, -345.6, etc.
one_weight and total_weight are both of type double
-
8/3/2019 Topic 2 Student Copy
8/46
Immediately prior to use
At the beginningTwo locations for variable declarations
int main(){
Variables declaration (2)
{int sum;sum = score1 +
score2;
return 0;
}
int sum;sum = score1 + score 2;
return 0;}
-
8/3/2019 Topic 2 Student Copy
9/46
Declaration syntax:
Data_type Variable_1 , Variable_2, . . . ;
Variables declaration (3)
double average, m_score, total_score;
double moon_distance;
int age, num_students;int cars_waiting;
-
8/3/2019 Topic 2 Student Copy
10/46
Assignment statement An assignment statement changes the value of a variable
total_weight = one_weight + number_of_bars; total_weight is set to the sum one_weight + number_of_bars
Assignment statements end with a semi-colon
The single variable to be changed is always on the leftof the assignment operator =
On the right of the assignment operator can be
Constants -- age = 21; Variables -- my_cost = your_cost;
Expressions -- circumference = diameter * 3.14159;
-
8/3/2019 Topic 2 Student Copy
11/46
The = operator in C++ is not an equal sign
The following statement cannot be true in algebra
Assignment statement and Algebra
=
In C++ it means the new value of number_of_bars
is the previous value of number_of_bars plus 3
_ _ _ _
-
8/3/2019 Topic 2 Student Copy
12/46
Exercise 1 Give good variable names for identifiers to store.
the speed of an automobile? an hourly pay rate?
the highest score on an exam?
Identify the following identifiers is valid or not. Net_income
4years_sale
Hour_p#y Year_1income
Y2kilo
-
8/3/2019 Topic 2 Student Copy
13/46
2.2 Understand data types 2 and 2.0 are not the same number
A whole number such as 2 is of type intA real number such as 2.0 is of type double
Numbers of type int are stored as exact values
Numbers of type double may be stored as
approximate values due to limitations on number of
significant digits that can be represented
-
8/3/2019 Topic 2 Student Copy
14/46
Data type (1)Integer (int)
Integer data types hold whole numbers
Type int does not contain decimal points
Examples: 34 45 1 89
a e e ow s ows an n eger a a ypes, s ze an range
-
8/3/2019 Topic 2 Student Copy
15/46
Data type (2)Float/double
The floating-point data types are:
They can hold real numbers such as:
12.45 -3.8Stored in a form similar to scientific notation
All floating-point numbers are signed
-
8/3/2019 Topic 2 Student Copy
16/46
Data type (3) Type float/double can be written in two ways
Simple form must include a decimal point Examples: 34.1 23.0034 1.0 89.9
Data type (3)
Examples: 3.41e1 means 34.13.67e17 means 367000000000000000.0
5.89e-6 means 0.00000589
Number left of e does not require a decimal point
Exponent cannot contain a decimal point
-
8/3/2019 Topic 2 Student Copy
17/46
Example:
Data type (4)
-
8/3/2019 Topic 2 Student Copy
18/46
Character (char)
Used to hold characters or very small integervalues
Data type (5)
Usua y 1 yte o memory Numeric value of character from the character
set is stored in memory:
-
8/3/2019 Topic 2 Student Copy
19/46
Example
Data type (6)
-
8/3/2019 Topic 2 Student Copy
20/46
2.3 : Know operators & expressionPRIMARY EXPRESSION
-
constantIdentifier expression
-
8/3/2019 Topic 2 Student Copy
21/46
ASSIGNMENT EXPRESSION
a =
variable Assignmentoperatorsexpression
-
8/3/2019 Topic 2 Student Copy
22/46
BINARY EXPRESSION
+
Firstoperand
operator Secondoperand
-
8/3/2019 Topic 2 Student Copy
23/46
POSTFIX OPERATOR
operand
a++
Postfix operator
(increment by 1)
-
8/3/2019 Topic 2 Student Copy
24/46
PREFIX EXPRESSION
operand
++a
unary operator
-
8/3/2019 Topic 2 Student Copy
25/46
Operator Can be classified according to:
The type of their operands and their output. Arithmetic
Logical
Boolean
The number of their operand.
Unary(one operand)
Binary(two operands)
-
8/3/2019 Topic 2 Student Copy
26/46
1. Arithmetic Operators (2)
-
8/3/2019 Topic 2 Student Copy
27/46
Arithmetic Operators (1)
-
8/3/2019 Topic 2 Student Copy
28/46
Arithmetic Operators (3)
-
8/3/2019 Topic 2 Student Copy
29/46
Arithmetic Operators (4)
-
8/3/2019 Topic 2 Student Copy
30/46
Arithmetic Operators (5)
-
8/3/2019 Topic 2 Student Copy
31/46
Arithmetic Operators (6)
-
8/3/2019 Topic 2 Student Copy
32/46
Example of Arithmetic operator
Arithmetic Operators (7)
-
8/3/2019 Topic 2 Student Copy
33/46
Arithmetic Operators (8)
-
8/3/2019 Topic 2 Student Copy
34/46
Arithmetic Operators (9)
-
8/3/2019 Topic 2 Student Copy
35/46
Arithmetic Operators (10)
-
8/3/2019 Topic 2 Student Copy
36/46
Exercise 2
-
8/3/2019 Topic 2 Student Copy
37/46
2. Relational Operator (1)
-
8/3/2019 Topic 2 Student Copy
38/46
Relational Operator (2)
-
8/3/2019 Topic 2 Student Copy
39/46
Relational Operator (3)
-
8/3/2019 Topic 2 Student Copy
40/46
3. Logical Operator (1)
-
8/3/2019 Topic 2 Student Copy
41/46
Logical Operator (2)
-
8/3/2019 Topic 2 Student Copy
42/46
Logical Operator (3)
-
8/3/2019 Topic 2 Student Copy
43/46
Formed by combining operators, variables and
constant. Examples:
Expression
ross_pay e uc ons
(basic_pay + hours * rate) (socso + premium + loan)
(b * b 4 * a * c) > 0
(sex == male || sex == female) && age >=21
-
8/3/2019 Topic 2 Student Copy
44/46
Mathematical formula and C expression
Mathematical operator C expression
+ +- -
*
/
OR ||
AND &&NOT !
-
8/3/2019 Topic 2 Student Copy
45/46
Example: Given the following formula
LCF
2832.6
1=
Convert to C expressionF = 1 / (6.2832 * sqrt (L * C))
-
8/3/2019 Topic 2 Student Copy
46/46
Exercise 3 Convert the following equation to C expression:
i. x = m2(m-q) + (p-n)
ii.
iii. -
5
2
= xy
)10
5.5( = xyw
Given integer variables, a = 5, b=7 and c=8, find thefollowing:
a / b + c
a + b x (c / a)
b % a + c
a b + c x (b / a x c)
top related