1. BASIC ELEMENTS OF A COMPUTER PROGRAM
CSC128 FUNDAMENTALS OF COMPUTER PROBLEM SOLVING

2. Arithmetic expression
Contents
Identifier 1
Rules for naming and declaring data variables 2
Basic data types 3
Arithmetic operators 4
Arithmetic expression 5
Assignment statement 6

3. IDENTIFIERS

4. Identifiers An identifier is a name assigned by the user.
It is to represent programming entities such as variable, function and constants.
Rules in naming an identifier:
The 1st character must be an alphabet letter or an underscore ‘_’.
Can only consists of letters, digits and underscore ‘_’.
Cannot use C++ reserved words/keywords
There must be no blank space character
Identifiers are case sensitive

5. Reserved Word It has predefined meaning for the language. int char
long
float
double
default
case
for
void
break
const
else if
private do
goto
switch
while
public
class
return
continue

6. Variable A location in computer memory to store data.
Can only store 1 value at a time
Value of a variable may change during program execution.
Must be declared before used.
Must always assign/ initialize a value to a variable before using the variable.

7. Variable Declaration
Syntax: data_type variable; Example: int x; int number1, number2, number3;
Please take note of the coma to
Separate the variable list &
Semicolon to end the variable declaration

8. Variable: what happen when a variable is declared??
The compiler allocates a memory space for the variable.
In the memory space, name, data type and value of the variable are stored.
ex.
Allocates a memory of 4 bytes with address the information stored in the memory space are variable name (area), data type (float).
float area;

9. Variable Rules
Must begin with a letter or underscore (_), and may only contain only letters, underscore, or digits.
Variable name cannot be a keyword.
Variable name cannot consists of more than 31 characters.

10. Constant
Values that are fixed and do not change throughout program execution
Declaring a constant:
Using const keyword

11. Constant Declaration
Syntax: const data_type constant_name = value; const float PI = 3.14;
type
const keyword
value
Constant_name

12. Legal and Illegal Identifiers
The following are legal identifiers in C++:
first
conversion
payRate

13. STANDARD DATA TYPES

14. Data Types Categories of data type Numeric data type
Character data type

15. Numeric Data Type Integer Floating point
Whole number – positive, zero or negative
C++ keyword
int, long
Floating point
Numbers with decimal points
float, double
int area;
float area;

16. int Data Type Examples: -6728 7878
Positive integers do not have to have a + sign in front of them
No commas are used within an integer
Commas are used for separating items in a list

17. float, double Data Type
Is a decimal number that contains the decimal point (.)or the exponent (e) or both.
float data type can hold values up to six or seven significant digit accuracy.
double data type can hold values up to 14 or 15 significant digit accuracy.

18. char Character Data Type char name; Single character Example:
Store one character value
C++ keyword
char
Example:
char name;

19. char Data Type The smallest integral data type
Used for characters: letters, digits, and special symbols
Each character is enclosed in single quotes
Some of the values belonging to char data type are: 'A', 'a', '0', '*', '+', '$', '&'
A blank space is a character and is written ' ', with a space left between the single quotes

20. char[] Data Type Sequence of characters
It stores sequence of zero or more characters
Enclosed in double quotation marks
Null: no characters is stored.
Each character has relative position
Position of first character is 0, the position of the second is 1, and so on
Length: number of characters in a sequence
C++ keyword
char[]
char name[5];
Note: the double quotes and
Single quotes

21. SUMMARY OF DATA TYPE Category Data types Keywords Bits Range Examples
Numeric
integer
int 16
to 32767
45, 0, -10
long integer
long 32 to
-37876
floating point
Float
6 digit precision
32.88, -89.5
double floating point
double 64
12 digit precision
Character
char 8
‘c’, ‘v’
Sequence of character
char[ ]
“hello”, “sarah”

22. Exercise Problem: to calculate area of a circle Data Data type
Variable name
Input
radius
float
Output
area
areaCircle
Process
areaCircle = 3.142*radius*radius

23. Exercises Problem: to compute the area of triangle. Data Data type
Variable name
Input
Output
Process

24. Exercise Problem: to display user’s name and retirement age Data
Data type
Variable name
Input
Output
Process

25. Initialization float rate = 0.0; double sale = 0.0; char grade = ‘ ’;
A variable can be initialized to any value as long as the value’s data type matches the variable’s data type.
Syntax:
datatype variable [ = initialValue ];
Examples:
int age = 0;
float rate = 0.0;
double sale = 0.0;
char grade = ‘ ’;
char company[20] =“ ”;

26. Exercises
Write a C++ statement that declare a variable name numberOfPeople. Assign the data type int to the variable and initialize it appropriately.
Write a C++ statement that declare a variable name interestRate. Assign the data type double to the variable and initialize it appropriately.
Write a C++ statement that declare a float variable named rate. Initialize the variable to the number 5.6

27. operators

28. OPERATORS
A Symbol that tells the compiler to perform specific mathematical or logical manipulations
Types of operator:
Arithmetic operators
Assignment operators
Relational operators
Logical operators

29. Arithmetic operator Addition Subtraction Modulus Multiplication
Division

30. Arithmetic operator Operation Operator Subtraction - Addition +
Multiplication *
Division /
Modulus %

31. Precedence & Associativity
Precedence of operator
Precedence rules:
specify which operator is evaluated first when two operators with different precedence are adjacent in an expression.
Associativity rules:
specify which operator is evaluated first when two operators with the same precedence are adjacent in an expression.
Highest
Operators
Associativity ()
Left to right
* / %
Lowest

32. Precedence & Associativity
Example 1:
Example 2: 4 + 2 * 3 3 * 4 / 2

33. Arithmetic expression

34. operands One of the input of an operator Example: 3 + 6 Operator

35. Several rules that you need to follow to evaluate arithmetic expression:
If one or more operand(s) in an arithmetic expression has/have data type double, the resulting expression is of data type double.
If all operands in arithmetic expression are of type int, the resulting expression is of type int.

36. Arithmetic operators Require two operands Ex. +, -, *, /, %
For the modulus (remainder) operator, all of its operands must be integer only.
Be careful of the operands’ data types when using division operator. For example,
Expressions
Output
7 / 4 1
7.0 / 4
1.75
-1 / 4
-1 / 4.0
-0.25

37. Example
3 * 7 – * 5 / (3 * 7) – 6 + ( (2 * 5) / 4 ) + 6 = 21 – 6 + (10 / 4) + 6 (Evaluate *) = 21 – (Evaluate /) = (Evaluate -) = (Evaluate first +) = 23 (Evaluate +)

38. Test yourself!!!! Examples : double a, b, c, d, e;
Declaration
double a, b, c, d, e;
Initialization
a = 10.0, b = 20.0, c = 15.0, d = 8.0,
e = 40.0;
Expression to be evaluated
(a + b / ( c – 5.0 )) / ((d + 7.0) / (e – 37.0) / 3.0)

39. Answer:
(a + b / ( c – 5.0 )) / ((d + 7.0) / (e – 37.0) / 3.0)
The sequence :
(c – 5.0) = 10.0
(d + 7.0) = 15.0
(e ) = 3.0
(a + b / 10.0) / (15.0 / 3.0 / 3.0)
(a + 2) / (5.0 / 3.0)
(12) / (1.667)
7.2

40. Thank You !