Algorithm, Program ,Pseudocode and Flowchart
Algorithm and Programs
Algorithm: a method or a process followed to solve a problem.
An algorithm takes the
input to a problem (function) and transforms it to the output. A problem can
have many algorithms.
Algorithm posses the
following properties:
1. It must be correct.
2. It must be composed of a series of concrete
logical steps in proper sequence.
3. There can be no ambiguity as to which step
will be performed next.
4. It must be composed of a finite number of steps.
5. It must terminate.
Example of
Simple C Program:
#include<stdio.h>
int
main()
{
int a, b, c;
printf("Enter two numbers to add\n");
scanf("%d%d",&a,&b);
c = a + b;
printf("Sum of entered numbers = %d\n",c);
return 0;
}
Pseudocode:
Pseudocode is
an informal high-level English-like representation or description of the
operating principle of a computer program or other algorithm logic. It
uses the structural conventions of a programming language, but is intended for human
reading rather than machine reading. It consists of an extended version of
the basic algorithmic constructs: sequence, selection, and iteration.
Features of PseudoCode:
- Algorithm Header
- Purpose, Condition, sequence and Return
- Statement Numbers
- Keyword and indentation with no fixed syntax
- Variables
- Constructive Statement
Pseudocode Example
Express an algorithm to get two
numbers from the user (dividend and divisor), testing to make sure that the
divisor number is not zero, and displaying their quotient using pseudocode
Example
1:
1. Declare variables: dividend, divisor, quotient
2. Prompt user to enter dividend and divisor
3. Get dividend and divisor
4. IF divisor is equal to zero, THEN
4.1. DO
4.1.1. Display error message, “divisor must be non-zero”
4.1.2. Prompt user to enter divisor
4.1.3. Get divisor
4.2. WHILE divisor is equal to zero
5. ENDIF
6. Display dividend and divisor
7. Calculate quotient as dividend/divisor
8. Display quotient
Example
2:
Flowchart:
A
graphical tool that diagrammatically depicts the steps and structure of an
algorithm or program. The
following shapes are often used in flowcharts:
 | |
| Basic Flow Chart Symbols |
Example of Pseudocode and Flow chart
 |
| Pseudocode and Flow chart of a problem |
