1. Fundamentals of C programming
- Ompal Singh
Sharda University,Gr.Noida

2. Sharda University,Gr.Noida
Topics
Algorithm
Pseudo code
Flow Chart
Sharda University,Gr.Noida

3. Planning of Computer Programming- In today’s world a computer is used to solve various types of problems because it takes very less time as compared to a human being.
1. Analyze the given problem
2. Divide the process used to solve the problem in a series of elementary task.
3. Formulate the algorithm to solve the problem.
Now in other words we say that “program must be planned before they are written”.

4. ALGORITHMS A typical programming task can be divided into two phases:
Problem solving phase
produce an ordered sequence of steps that describe solution of problem
this sequence of steps is called an algorithm
Implementation phase
implement the program in some programming language

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Algorithm
The Term Algorithm refers to the logic of a program. It is a step-by-step description of a solution to the given problem.
When sequence of instructions are executed in the specified format and sequence the desired result are obtained.
Definition:- A format or set of steps for solving a particular problem is called as algorithm.
It has clear starting and stopping point. With specific step by step instructions in each line.
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6. Characteristics of Algorithm
Each instruction should be precise and clear.
Each instruction should be executed in a finite time.
One or more instructions should not be repeated Infinitely.
After executing the instructions the desired result are obtained.
It range from Simple to the Complex.
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7. Sharda University,Gr.Noida
Process of algorithm
An algorithm must express the steps in the solution in a way that will be suitable for computer processing.
It Read Value perform a simple procedure and output the required result.
After algorithm a Flowchart is prepared and than it is run in the language form in the computer.
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8. Three constructs

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Algorithm
Find area of a rectangle
Step 1: Input L,B
Step 2: area=L*B
Step 3: Print area
Step 4: Exit
Find the area of a circle
Step 1: Input R
Step 2: area=3.14*R*R
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10. Sharda University,Gr.Noida
Step 1: Input SP,CP
Step 2: if (SP>CP) then
p=SP-CP
Print p
else
l=CP-SP
Print l
endif
Step 3:Exit
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11. Sharda University,Gr.Noida
Detailed Algorithm
Step 1: Input M1,M2,M3,M4
Step 2: GRADE  (M1+M2+M3+M4)/4
Step 3: if (GRADE < 50) then
Print “FAIL”
else
Print “PASS”
endif
Step 4:Exit
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12. Sharda University,Gr.Noida
Step 1: Input N1, N2, N3 Step 2: if (N1>N2) then if (N1>N3) then MAX ← N1 [N1>N2, N1>N3] else MAX ← N3 [N3>N1>N2] endif if (N2>N3) then MAX ← N2 [N2>N1, N2>N3] MAX ← N3 [N3>N2>N1] Step 3: Print “The largest number is”, MAX
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13. Sharda University,Gr.Noida
Detailed Algorithm
Step 1: Input M1,M2,M3,M4
Step 2: GRADE  (M1+M2+M3+M4)/4
Step 3: if (GRADE > 60) then
Print “Ist”
elseif (GRADE > 50)and (GRADE <60) then
Print “IInd”
else
Print “Fail”
endif
Step 4:Exit
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14. Sharda University,Gr.Noida
Step 1: Input the value of N
Step 2: Set i=1
Step 3: Repeat step 4 and 5 until i<=N
Step 4: Print i
Step 5: Set i=i+1
end loop
Step 6: Exit
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Pseudo code
First produce a general algorithm (one can use pseudo code)
Refine the algorithm successively to get step by step detailed algorithm that is very close to a computer language.
Pseudo code is an artificial and informal language that helps programmers develop algorithms. Pseudo code is very similar to everyday English.
Sharda University,Gr.Noida

16. Sharda University,Gr.Noida
Pseudocode
Pseudocode is an informal description of an
algorithm
English-like statements that require less precision
than a formal programming language.
Allows the designer to focus on the logic of the
algorithm without being distracted by details of
language syntax.
A good pseudocode algorithm should be
independent of, but easily translated into, any formal
programming language.
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17. Pseudocode Control Structures
Sequence control structures
Instructions are performed linearly
Conditional control structures
A choice/selection is made between multiple
courses of action
Looping/iteration control structures
Enables repeating instructions within the algorithm
A test condition determines when the repetition
ends
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18. Pseudocode Control Structures
Selection and conditional
1. if (condition) then
2. statement 1
3. ...
4. endif
• If the (condition) is TRUE then statements between THEN and ENDIF are executed once
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Two-way decision
1. if (condition) then
2. statement 1
3. ...
4. else
5. statement n+1
6. ...
7. endif
• If the (condition) is TRUE then statements between THEN and ELSE are executed once
• If the (condition) is FALSE then statements between ELSE and ENDIF are executed once
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LOOP
For Loop– Used to implement statements that needs to be repeated a fixed number of times.
1. for i ←1 to n
2. Statement 1
3. ...
4. next i
• i is the index or counter that starts with some value and increases by one every time through the loop until it reaches the given maximum value
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Repeat …until
Repeat Loop– Used to implement statements that needs to be repeated until the condition becomes TRUE.
1. repeat
2. Statement 1
3. ...
4. until (condition)
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While LOOP
While Loop– Used to implement statements that needs to be repeated while the condition is TRUE.
1. while (condition)
2. Statement 1
3. ...
4. endwhile
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23. Sharda University,Gr.Noida
Advantages
Converting a pseudo code to a programming language is easier than converting a flow chart to programming language.
It is easier to modify the pseudo code of a program logic when program modification is necessary.
Required less time and effort than flow chart.
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Limitations
A graphical representation of program logic is not available.
There are no standard rules to follow in using pseudo code.
It is very difficult for beginners.
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Pseudocode
Example 1: Write an algorithm to determine a student’s final grade and indicate whether it is passing or failing. The final grade is calculated as the average of four marks.
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Pseudocode
Pseudocode:
Input a set of 4 marks
Calculate their average by summing and dividing by 4
if average is below 50
Print “FAIL”
else
Print “PASS”
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27. Sharda University,Gr.Noida
Flowchart
A Flowchart is a pictorial representation of an algorithm.
The First flowchart is made by John Von Newman in 1945.
It is a symbolic diagram of operation sequence, dataflow, control flow and processing logic in information processing.
The symbol used are simple and easy to learn.
It is a very help full tool for programmers and beginners.
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28. Sharda University,Gr.Noida
The Flowchart
(Dictionary) A schematic representation of a sequence of operations, as in a manufacturing process or computer program.
(Technical) A graphical representation of the sequence of operations in an information system or program. Information system flowcharts show how data flows from source documents through the computer to final distribution to users. Program flowcharts show the sequence of instructions in a single program or subroutine. Different symbols are used to draw each type of flowchart.
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29. Sharda University,Gr.Noida
The Flowchart
A Flowchart
shows logic of an algorithm
emphasizes individual steps and their interconnections
e.g. control flow from one action to the next
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30. Sharda University,Gr.Noida
Purpose of flowchart
Provide Communication.
Provide an overview.
Show all elements and its relationship.
Quick method of showing program flow.
Check program logic.
Facilitate coding.
Provide program revision.
Provide Program documentation.
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31. Advantages of flowchart.
Communication.
Effective analysis.
Proper documentation.
Efficient coding.
Proper debugging.
Efficient program maintenance.
Easy and clear presentation.
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32. Limitation of flowchart
Complex logic.
Drawing is time consuming.
Alteration and modification.
Redrawn many times.
Difficult to draw and remember.
Reproduction ( replica ).
Technical detail.
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33. Symbols used in flowchart
All symbols are of different shape and size.
All have specific meaning and use.
The ANSI ( American National Standard Institute) group categories symbols in 3 types basic, specialized and additional symbols.
These institution and standardized these basic symbols for use.
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BASIC SYMBOLS
Terminal Symbol = for start and stop.
INPUT and OUTPUT = Any function of input and output data.
Processing = An arithmetic and data movement instruction. Shows mathematical calculation and logic operations.
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35. Sharda University,Gr.Noida
SYMBOLS
Decision = Diamond indicate decision point in the program flow. IT may have 2 way branch or 3 way also.
Flow Lines = A Straight line between two boxes shows the path of logic flow in the program. An arrow head on the top of the line shows the direction of the flow, data from top to bottom and left to right.
Connectors = 2 small circles are used to connect separated portions of a flowchart without drawing lines between the parts. One connector indicated where the flow breaks off the other where it resumes.
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36. Sharda University,Gr.Noida
Flowchart Symbols
Basic
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37. Flowcharts for three constructs

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Example
START
Input
M1,M2,M3,M4
GRADE(M1+M2+M3+M4)/4 IS
GRADE<50
PRINT
“FAIL”
STOP Y N
Step 1: Input M1,M2,M3,M4
Step 2: GRADE  (M1+M2+M3+M4)/4
Step 3: if (GRADE <50) then
Print “FAIL”
else
Print “PASS”
endif
PRINT
“PASS”
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39. Sharda University,Gr.Noida
Example 2
Write an algorithm and draw a flowchart to convert the length in feet to centimeter.
Pseudocode:
Input the length in feet (Lft)
Calculate the length in cm (Lcm) by multiplying LFT with 30
Print length in cm (LCM)
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40. Sharda University,Gr.Noida
Example 2
Algorithm
Step 1: Input Lft
Step 2: Lcm  Lft x 30
Step 3: Print Lcm
Flowchart
START
Input
Lft
Lcm  Lft x 30
Print
Lcm
STOP
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41. Sharda University,Gr.Noida
Example 3
Write an algorithm and draw a flowchart that will read the two sides of a rectangle and calculate its area.
Pseudocode
Input the width (W) and Length (L) of a rectangle
Calculate the area (A) by multiplying L with W
Print A
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42. Sharda University,Gr.Noida
Example 3
Algorithm
Step 1: Input W,L
Step 2: A  L x W
Step 3: Print A
START
Input
W, L
A  L x W
Print A
STOP
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43. Sharda University,Gr.Noida
Example 4
Write an algorithm and draw a flowchart that will calculate the roots of a quadratic equation
Hint: d = sqrt ( ), and the roots are: x1 = (–b + d)/2a and x2 = (–b – d)/2a
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44. Sharda University,Gr.Noida
Example 4
Pseudocode:
Input the coefficients (a, b, c) of the quadratic equation
Calculate d
Calculate x1
Calculate x2
Print x1 and x2
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45. Sharda University,Gr.Noida
Example 4
Algorithm:
Step 1: Input a, b, c
Step 2: d  sqrt ( )
Step 3: x1  (–b + d) / (2 x a)
Step 4: x2  (–b – d) / (2 x a)
Step 5: Print x1, x2
START
Input
a, b, c
d  sqrt(b x b – 4 x a x c)
Print
x1 ,x2
STOP
x1 (–b + d) / (2 x a)
X2  (–b – d) / (2 x a)
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46. Example 5

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Thank you
Ompal Singh
Sharda University,Gr.Noida

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