Problem Solving with Programming

1
Problem Solving with Programming

• Week 2
• Department of Computer Science
• Faculty of Science and Technology
• Assumption University

2
Agenda

• Program Modeling Tools
• Flowchart
• Pseudo code
• Programming Style Conventions
• Indentation and Code Formats
• Naming Conventions
• Commenting
• Number Systems
• Decimal
• Binary
• Hexadecimal
• Octal

3
Program Modeling Tools
3
4
Flowchart

• A flowchart is a diagram that is used to describe
  how a program work.
• It is used mainly to indicate the sequence of
  program executions as well as program branches
  and iterations.

5
Flowchart Symbols

• Start/Stop
• Computation
• Input/Output
• Condition
• Directions
• Connection

6
Flowchart Start/Stop
. . .
7
Flowchart Sequential
8
Flowchart Condition
9
Flowchart Iterations
10
Pseudocode

• Pseudocode is used to describe algorithm.
• It is written in human languages (usually
  English).
• There is no standard conventions on how to write
  pseudocode.
• Pseudocode is usually written as steps on how to
  do something.
• Programmers can write a pseudocode first and then
  translate it in to a program in a specific
  programming language.

11
Programming Style Conventions
11
12
Indentation and Code Formats

• Indentation and code formats are not required for
  most programming languages but they are important
  for program readability.
• It helps programmers convey the structure of a
  program or a block of code to human readers.

13
Indentation in C

• In C, an indentation is used whenever the line
  of code is a part of the outer one.
• For example
• int Add(int a, int b)
• return a b

14
Nested Indentation

• Indentation can be nested if an inner code has
  something further in it.
• For example
• if (a lt b)
• if (a lt c)
• x a
• else
• x c

15
Curly Braces

• In C, the curly braces and are used to
  define the scope and create a compound statement.
• The opening brace must be on the same line as
  the control structures first line.
• The closing brace must be on the last line of
  that control structure.
• The location of the closing brace must be at the
  same indentation level as that of control
  structure.

16
Naming Conventions

• Good naming leads to good program readability.
• Naming conventions specify how to capitalize
  names (such as variables and functions), whether
  there is any prefix or suffix to specialize names
  (such as pointers),

17
C Naming Conventions

• Names representing types must be in mixed case
  starting with an uppercase letter (e.g., Student,
  MobilePhone).
• Variable names must be in mixed case starting
  with a lowercase letter (e.g., studentName,
  mobileNumber).
• Named constants must be all uppercase using
  underscore to separate words (e.g., PI,
  MAX_VALUE).

18
C Naming Conventions

• Names representing functions must be verbs and
  written in mixed case starting with a lowercase
  letter (e.g., getStudentName, setMobileNumber).
• Abbreviations and acronyms must not be uppercase
  when used as name (e.g., DvdPlayer).

19
Commenting

• Commenting is used to document your code.
• It describes what does the code or a segment of
  the code does.
• It also helps other programmers understand your
  code.

20
Commenting in C

• There are two ways to comment in C
• Start a comment line with //
• Cover a comment with / and /

21
Number Systems

• Number systems use positional notation to
  represent value
• Four such systems used in practice are
• Decimal number system
• Binary number system
• Hexadecimal number system
• Octal number system

22
Decimal Number System

• The decimal number system has ten unique symbols
  0, 1, 2, 3, 4, 5, 6, 7, 8, and 9
• It is also called Base 10 number system
• the system of counting has ten symbols
• Its radix or base is said to be 10
• For example
• (3472)10 3 103 4 102 7 101 2 100
• 3000 400 70 2
• (536.15)10 5 102 3 101 6 100 1
  10-1 5 10-2

23
Binary Number System

• The binary number system has only two symbols 0
  and 1
• Hence the radix or base is said to be 2
• For example
• (10101)2 1 24 0 23 1 22 0 211
  20
• 16 0 4 0 1
• 21 (the decimal equivalent of 1011012)

MSB
LSB
MSB Most Significant Bit LSB Least Significant
Bit
24
Binary Number System Cont.

• What is the decimal equivalent of 11001.0112 ?
• 11001.0112
• 124 123 022 021 120
  02-1 12-2 12-3
• 16 8 0 0 1 0 0.25 0.125
• 25.375

25
Decimal to Binary Conversion

• Convert the following decimal numbers into their
  binary equivalent
• 17
• 251
• 4372
• 0.71
• 23.567

26
Binary to Decimal Conversion

• Convert the following binary numbers into their
  decimal equivalent
• 101102
• 11101112
• 10.0112
• 11.10112

27
Hexadecimal Number System

• Base-16 number system is called hexadecimal
  system
• The term hexadecimal comes from the combination
  of two words decimal (10) and hex (6)
• 16 characters exists in the hexadecimal set 0,
  1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F
• This number system is most important in digital
  systems because it is easily to convert to and
  from binary

28
Binary to Hexadecimal Conversion

• Convert 110111101011102 into hexadecimal
• 0011 0111 1010 1110
• 3 7 A
  E
• 37AE16 37AEH

29
Hexadecimal to Decimal Conversion

• Convert A59CH into decimal
• A59CH A 163 5 162 9 161 C 160
• 40960 1280 144 12
• 42396

30
Hexadecimal to Binary Conversion

• Convert F37AH into Binary
• F37AH 1111 0011 0111 1010
• Convert 23E0.B2H into Binary
• 23E0.B2H 0010 0011 1111 0000 . 1011 0010

31
Octal Number System

• The octal number system has 8 symbols 0, 1, 2,
  3, 4, 5, 6, and 7
• Hence it is called Base-8 number system
• Convert (231)8 into decimal
• (231)8 2 82 3 81 1 80
• 128 24 1 153
• Convert 11110111101012 into octal
• 001 111 011 110 101
• 1 7 3
  6 5 (17365)8