# Exchanging values of two variables

#### Exchanging values of two variables

**Problem definition: **Exchanging values of two variables.

**Analysis:** Two variables x and y contains two different values.

Swap the values of x and y such that x has y′s value and y has x′s value.

**Solving by example:** Let us consider two variables x and y,containing values 8 and 20 respectively.

The original values of x and y are:

The requirement is once the algorithm is performed, the results should be

If you think by just saying,

x=y; y=x;

The value gets swapped, then you are mistaken.

These instruction are atomic in nature and hence x = y means that the value of ‘x’ is lost.

So,we have to use a temporary variable,temp to store the value of ‘x’.

The value of ‘x’ and ‘y’ is swapped.

**Algorithm Definition**

**Question. What is algorithm? Write the characteristics of an algorithm. Give an example for algorithm. **

**Answer :**

**Definition of Algorithm**

Algorithm is a step by step solution to a given problem. Sequence of steps written in order to carry out some particular task. Each step of an algorithm is written in english.

Various characteristics of an algorithm are

- The algorithm must have definite start and end.
- An algorithm may accept zero or more inputs
- An algorithm must produce at least one output
- The steps of an algorithm must be simple, easy to understand and unambiguous.
- Each step must be precise and accurate.
- The algorithm must contain finite number of steps.

**Example:**

**Algorithm 1: Algorithm for finding of area of triangle**

Step 1: start

Step 2: Read base and height of traingle

Step 3: Calulate area of traingle

Step 4: print area of traingle

Step 5: stop

**Algorithm 2: Algorithm for finding of sum and average of given three numbers**

Step 1: start

Step 2: Read three numbers i.e. A, B and C

Step 3: find sum of three numbers i.e. sum=A+B+C

Step 4: find average of three numbers i.e. average=sum/3

Step 4: print sum and average

Step 5: stop

**Question : What is pseudocode? Give an example for pseudocode. **

**Answer:**

**Definition of Pseudocode**

Pseudocode is high level description of an algorithm that contains a sequence of steps written in combination of english and mathematical notations to solve a given problem.

Pseudocode is part english and part program logic. Pseudocodes are better than algorithm since it contains ordered steps and mathematical notations they are more closer to the statements of programming language.

This is essentially an intermediate-step towards the development of the actual code(program). Although pseudo code is frequently used, there are no set of rules for its exact writing.

**Example:**

**Pseudocode 1: Pseudocode for finding area of traingle**

Pseudocode Area_of_Traingle

BEGIN

READ base and Height

CALCULATE Area_of_Triangle=(base*height)/2

PRINT Area_of_Triangle

END

**Pseudocode 2:Pseudocode for finding sum and average of three numbers**

Pseudocode SUM_AVG

BEGIN

READ A, B, and C

CALCULATE sum=A+B+C

CALCULATE average=SUM/3

PRINT sum and average

END

**Question : What is flowchart? List and define the purpose of symbols used to
represent flowchart. Give an example for flowchart.**

**Answer :**

**Definition of flowchart**

Flowchart is a graphical or pictorial representation of an algorithm. Its a program "design tool in which standard graphical symbols are used to represent the logical flow of data through a function.

Flowchart is a combination of symbols. They show start and end points, the order and sequence of actions, and how one part of a flowchart is connected to another.

**Example:**

**Finding the area of triangle **