Introduction to Computer
Programming
Engr Asma Ali
• Course Code:
• Credit Hours:
• Pre-requisite(s):
• Email Address:
CS-1301
2+1
None
asma.ali@kiet.edu.pk
Books:
• Text Book:
Problem solving and program design in C by Jeri R. Hanly,
Elliot B. Koffman. (7th edition)
• Reference Books:
C - How To Program By Deitel
Content :
1.
2.
3.
4.
5.
6.
What is Flowchart
Flowchart Building Block
Decimal-to-Binary Conversion
What is Algorithm
Tips to Write Good Pseudo Code
Machine Language versus HLL
FLOWCHART
WHAT IS A FLOWCHART?
• A flowchart is simply a graphical representation of steps. It shows steps in
sequential order and is widely used in presenting the flow of algorithms,
workflow or processes.
WHEN TO USE A FLOWCHART?
• To develop understanding of how a process is done
• To study a process for improvement
• To communicate to others how a process is done
• To document a process
• When planning a project
Flowchart Symbols
• Different flowchart shapes have different conventional meanings. The
meanings of some of the more common shapes are as follows:
Example: Write a program calculating the sum
of two numbers:
Example: Find the largest among three different
numbers entered by the user.
Decimal-to-Binary Conversion
• Convert the following decimals into binary :
1.
2.
3.
4.
23
26
29
28.125
What is Algorithm
• A set of step to accomplish a task.
• An algorithm describes the step by step action to solve a problem.
• An algorithm has a well defined sequence of steps, it gives you an
output, and it will eventually terminate
• List of steps for solving a problem.
• There are many models supporting the development of the code:
• Pseudo code
• Structure Diagram
• Flowcharts
Example
• Write an algorithm and draw a flow chart to compute the average of
three numbers.
Declare a variable a,b,c and avg as int;
Read two numbers a,b and c;
avg=(a+b+c)/3;
Print avg;
Assignment:
• Write an algorithm and flow chart to find the area of rectangle.
• Write an algorithm and flow chart of square of number.
• Write algorithm and draw flowchart to find largest number among
two numbers.
Pseudo Code
• An algorithm is a systematic logical approach used to solve problems
in a computer while Pseudo code is the statement in plain English
which may be translated later into a programming language
(program).
• Pseudo-code is just a syntax of the communication about solving a
problem. This means that the algorithm is an actual way a problem is
solved while the pseudo-code is just a way of expressing that way.
Pseudo Code:
• Uses phrases to outline the task
• Easy to read and write
• Allow the programmer to concentrate on the logic of the problem
• Structured in English language
• Pseudo code is "halfway" between English and a programming
language.
• It is a description of a process in detail, though not necessarily in full
sentences.
• The key is to provide enough information so that anyone could follow
the instructions
Pseudocode  Write a program calculating
the sum of two numbers:
Pseudocode are English-like statements that
follow a loosely defined syntax and are used
to convey the design of an algorithm.
Version 1:
Version 2:
PROGRAM Add Two Numbers
READ two numbers
ADD the numbers
WRITE the sum
END PROGRAM
PROGRAM Add Two Numbers
READ First
READ Second
Sum = First + Second
WRITE Sum
END PROGRAM
Programming Languages:
• Various programming languages enable people to tell computers
what to do
• Foundation for developing applications
The Language Translation Process:
• How are Programs Understood by the Computer?
Program written in
programming
language
(source code)
Translator program

Assembler

Compiler

Interpreter
Program written in
machine language
(object code)
Processed
By CPU
Programming Languages
• Machine Language
(first generation of programming languages)
• The computer’s ‘natural language’
• Composed of binary digits (0s, 1s)
• The only language that computers understand
• Assembly Language
(second generation of programming languages)
• One-to-one correspondence to machine language
• Somewhat more user-friendly than machine language (mnemonic rather than binary digits)
• Assembler – program that translates an assembly language program into machine language
Programming Languages:
• Procedural Languages (High Level Languages)
(third generation languages)
•
•
•
•
•
•
One instruction translates into many machine language instructions
Programs describe the computer’s processing step-by-step
Closer to natural language; uses common words rather than abbreviated mnemonics
Examples: C, Fortran, QuickBasic
Compiler - translates the entire program into machine language
Interpreter - translates and executes one source program statement at a time
Programming Languages:
• Nonprocedural Language
(fourth generation languages)
• Allows the user to specify the desired result without having to specify the detailed
procedures needed for achieving the result
• Example: data base query language - SQL
• Can be used by non technical users
• Natural Language Programming Languages
(fifth generation (intelligent) languages)
• Translates natural languages into a structured, machine-readable form
• Are extremely complex and experimental
Processing A High Level Language Program:
Steps to execute a program written in C:
1. Use an editor to create a program. (source program)
2. Compiler translate the program in to an equivalent machine language. (object program)
3. The programs that you write in a high-level language are developed using a software development kit
(SDK), which contains many programs that are useful in creating your program. This prewritten code
resides in a place called the library.
4. Linking programs: The linker assembles all of functions (source and system’s) into final executable
program.
5. The next step is to load the executable program into the main memory for execution and a program
called loader accomplishes this.
6. The final step is to execute the program.
THANK YOU