⯈Algorithm and its Characteristics

⯈Elementary Problems

- Addition of two numbers
- Calculate area and circumference of circle
- Calculate area of triangle
- Calculate simple interest
- Calculate slope and distance between two points
- Convert length in feet to inches
- Weighted score in exam
- Convert temperature in degree Celsius to Fahrenheit
- Swap two numbers
- Swap two numbers without using extra variable

- Overview of C Programming Language
- Getting started with C Programming Language
- Keywords
- Identifiers
- Constants
- Operators
- Expression Evaluation
- Mathematical expression to C equivalent expressions
- Datatypes
- Variables
- Integer representation in C
- Character representation in C
- Type conversion in C
- sizeof operator
- Comments
- Mathematical Functions
- input output statements
- width specifiers in C
- structure of a C program
- header files
- Compilation process of a C program
- Types of initializations.

⯈Basic C Programs

- C program to add two numbers
- C program to find area and circumference of circle
- C program to swap two numbers
- C program to swap two numbers without using extra variable
- C program to swap two numbers using bitwise XOR
- C program to convert temperature in Celsius to Fahrenheit
- C program to calculate gross salary of an employee
- C program to count number of digits in a positive integer
- C program to count number of digits in binary representation
- C program to count number of digits in base ‘K’
- C program to convert kilometer to meter, feet, inches and centimeters
- C program to find first and last digit of a number
- C program to find minimum number of currency denominations
- C program to convert cartesian coordinates to polar coordinates
- C program to find distance between two places on earth in nautical miles
- C program to find slope and distance between two points
- C program to add 1 to the number using ‘+’ operator
- C program to find maximum of two numbers using ternary operator
- C program to find maximum of three numbers using ternary operator
- C program to find kth bit of a number
- C program to find last four bits of a byte

## Algorithm and Flowchart to calculate area and circumference of circle

Whenever we write an algorithm or program, **we always start with reading the input.** The input to this algorithm is **radius (R)** of a circle.

Formula:

area of circle = ΠR^{2} ,

circumference of circle = 2ΠR.

**Note:**

**The value of Pi is constant, and constants should not be read as an****input.****Read only the values of variables that are part of input.**

So, lets read the radius, hence we write **Read radius as R**

After reading all the necessary inputs it’s the time to calculate the area and circumference.

**a = ΠR ^{2}**

**c = 2ΠR**

Then we need to output the results. The results are stored in variables **a** **and c**.

**Note: Variables names are case – sensitive.**

Therefore, we write

**Display a**

**Display c**

### Algorithm:

**Name of Algorithm: Compute area and circumference of circle.**

Step 1: Start

Step 2: Read radius as R.

Step 3: **a = ΠR2**

**c = 2ΠR**

Step 5: Display **a **[outputs the content stored in variable ‘a’]

Step 6: Display **c **[outputs the content stored in variable ‘c’]

Sep 7: Stop

**Note: We can use mathematical symbols in an algorithm, but cannot be used in programs.**

### Flowchart:

### Tracing:

Let us do the dry run of the above algorithm:

In step 2, we read the value of radius (R). Let R = 1.5

In step 3 and step 4 we calculate area and circumference and store the result in ‘a’ and ‘c’ respectively.

a =22/7 * 1.5^{2} = 7.071

c = 2 * 22/7 * 1.5 = 9.428

In step 5, and 6, we display the value stored in variable** a and c**. Therefore we output **7.071 and 9.428**