Problem Solving Algorithm Flow Chart Programming Computer Languages Low Level Languages High Level Languages

1. Introduction to Computer
Lecture # 12
Course Instructor : Sehrish Rafiq
Govt. Girls Degree College Maneri Swabi
Higher Education Department KP

2. Lecture Overview
 Problem Solving
 Algorithm
 Flow Chart
 Programming
 Computer Languages
 Low Level Languages
 High Level Languages

3. Steps of solving a problem
 Identify, analyze and define the problem
 Design algorithm
 Draw Flow chart
 Transform the algorithm in to a computer program
 Test and debug the code
 Execute and save the program

4. Algorithm
 An algorithm is a step by step method of solving a problem.
 It is a detailed series of instructions for carrying out an operation or solving
a problem.
 Algorithms must have finite number of steps and should be completed in
finite time.
 These steps / instructions should be carried out in sequence defined by the
programmer.
 An algorithm should be defined in such a way that it reflect a clear picture
of the solution to the problem.
 We use algorithms in everyday tasks also, such as a recipe to bake a cake or
plan for going to college.

5. Continued…
 Algorithms do not follow any programming language.
 They can be written in simple English or using special notation
(pseudocode symbols).
 Algorithm cannot be executed on computer without converting it in
to program.
 To make a computer do anything, the algorithm has to be converted
in to a computer program.
 The computer then "executes" the program, following each step
mechanically, to accomplish the end goal.

6. Algorithm for adding two numbers
Step 1 :- Print “Enter any two numbers”
Step 2 :- Input a
Step 3 :- Input b
Step 4 :- Sum:= a + b
Step 5 :- Display Sum
Step 6 :- Exit

7. Flow Chart
 A flow chart is a graphical or symbolic representation of the steps of
an algorithm.
 Each step in the algorithm is represented by a different geometrical
symbol which contains a short description of the step.
 These symbols are linked together with arrows showing the
algorithm flow.

8. Flow Chart Symbols

9. Flow Chart Example
Start
Stop
Input a
Input b
Print “Enter any
two numbers”
Sum:= a + b
Display Sum

10. Programming
 Programming is the process of writing instructions in a particular
programming language for a computer to perform some specific activity.
 These set of instructions are known as programs and are stored in
computer memory.
 Before execution data and programs must be loaded in to RAM.
 When programs are executed, they produce the desired result.
 Program / set of programs are also known as software.

11. Program in C
# include< iostream.h >
#include< conio.h >
void main( )
{ int a, b, sum;
cout<<“Print any two numbers”<<endl;
cin>> a; cin>>b;
sum=a+b;
cout<< “Sum=”<<sum;
getch();
}

12. Computer Languages
 Language is a source of communication between human beings.
 Similarly, a programming language is a source of communication between
the programmer and computer.
 A programming language is a vocabulary and set of grammatical rules for
instructing a computer or computing device to perform specific tasks.
 Each programming language has a unique set of keywords (words that its
translator understands) and a special syntax for organizing program
instructions.
 The programmers have to write their code according to the rules specified
by the particular programming language, they are using.

13. Continued…
 There are two types of computer languages.
 Low Level languages
 High Level languages

14. Computer Languages

15. Low Level Languages
 Low level languages are machine codes or close to it.
 They are machine dependent or hardware architecture dependent which
means that programs written in a low level language on one type of
computer cannot be executed on another type of computer.
 There are two types of low level languages.
 Machine Language
 Assembly Language

16. Machine language
 Machine language is the lowest and most elementary language and is the
first type of programming language developed.
 Machine language is basically the only language which a computer can
understand.
 In fact, a manufacturer designs a computer to obey just one language, its
machine code, which is represented inside the computer by a string of
binary digits (bits) 0 and 1.
 The symbol 0 stand for the absence of an electric pulse and 1 for the
presence of an electric pulse.
 Since a computer is capable of recognizing electric signals, therefore, it
understands machine language.
 The set of binary codes which can be recognize by the computer is known
as its machine code instruction set.

17. Continued…
 A machine language instruction consists of an operation code and one or
more operands.
 The operation code specifies the operation to be performed e.g. read, record
etc.
 Operands identify the quantities to be operated on e.g. the numbers to be
added or the locations where data are stored.
 But, it is almost impossible to write programs directly in machine code.
 For this reason, programs are normally written in assembly or high level
languages and then are translated in the machine language by different
translators.

18. Machine Language
Advantages
 It makes fast and efficient use of the computer
 It requires no translator to translate the code i.e. directly understood
by the computer.
Disadvantages
 All operation codes have to be remembered
 All memory addresses have to be remembered
 It is hard to amend or find errors in a program written in the machine
language
 These languages are machine dependent i.e. a particular machine
language can be used on only one type of computer.

19. Assembly Language
 Assembly language was developed to overcome the problems of machine
language programmers.
 In Assembly language operation codes and operands are given in the form
of alphanumeric symbols instead of 0’s and 1’s.
 These alphanumeric symbols are known as mnemonic codes and can have
maximum up to 5 letter combinations e.g. ADD, SUB, MUL, DIV, JUMP,
LOAD, STORE, START, LABEL etc.
 Assembly language is also known as “Symbolic Programming Language”.
 Assembly language is also machine dependent like machine language which
means that assembly language code written for one machine cannot be
executed by another machine.

20. Continued…
 This language is very difficult and needs a lot of practice to master it
because very small English support is given..
 The instructions of the assembly language will also be converted to
machine codes by assembler to be executed by the computer.

21. Assembly Language
Advantages
 It is easier to understand and use as compared to machine language.
 It is easy to locate and correct errors.
 It is modified easily as compared to machine language.
Disadvantages
 Like machine language it is also machine dependent
 Since it is machine dependent, there programmer should have the
knowledge of he hardware also.

22. High Level Language
 High level computer languages give formats close to English language.
 The purpose of developing high level languages is to enable people to
write programs easily and in their own native language environment
(English).
 High-level languages are basically symbolic languages that use English
words and/or mathematical symbols rather than mnemonic codes.
 Each instruction in the high level language is translated into many
machine language instructions thus showing one-to-many translation.
 Examples of High Level Languages are :- C, C++,C#, Java, Python etc.

23. Advantages
 User-friendly (people based).
 Similar to English with vocabulary of words awl symbols therefore it is
easier to learn.
 They require less time to write.
 They are easier to maintain.
 Problem oriented' rather than 'machine' based.
 Shorter than their low-level equivalents, One statement translates into
many machine code instructions.
 It is independent of the machine on which it used i.e. programs developed
in high level language can be run on any computer for which there exists an
appropriate translator.

24. Disadvantages
 A high-level language has to be translated into the -machine language by a
translator and thus a price in computer time is paid.
 The object code generated by a translator might be inefficient compared to
an equivalent assembly language program.