What is algorithm in C?

What is an algorithm?

• In computer programming languages, an algorithm is set of statement that solves a particular problem.
• In C, first step of every algorithm is Start and last step of every algorithm is End. The solution for a problem is represented within Start and End statements.
• Consider a real world problem as a housewife wants to cook a dish, so she will first collect the ingredients, process the ingredients and finally make dish. The same steps are used to write an algorithm.

In simple words, algorithm can be summarized as:

1. Take the input
2. Perform some operations on the input to solve the problem
3. Get the output

Characteristics of good algorithm

The characteristics of a good algorithm are as follows:

1. Clear and Unambiguous: Each instruction in an algorithm should be unambiguous, i.e., there should be only one meaning of the statement and the meaning of it should be clear
2. Input: The number of input can be zero or more than zero which will be given to the algorithm.
3. Output: An algorithm should produce at least one result/output to the given problem.
4. Finiteness: There should be finite number of steps in an algorithm and the algorithm shouldn’t go into infinite loop.
5. Effectiveness: Each instruction should be effective as each instruction is affecting the entire algorithm.
6. Language independent: An algorithm should be independent of language. Because if algorithm is language-independent then algorithm can solve the problem using any language.

Any algorithm that satisfies above all given characteristics is consider as a good algorithm.

How to write an Algorithm?

1. Identify the problem which needs to be solved using algorithm.
2. Identify the conditions of the problem that need to take into consideration while designing an algorithm.
3. What input the algorithm will take.
4. Identify what will be the output after successfully following each step of an algorithm
5. At last, solution to the problem through the algorithm.

Examples

Example 1 – Algorithm to multiply two numbers in C

The algorithm to multiply the two numbers in C is as follows:

Step 1: Start

Step 2: Declare no1, no2 and mul_of_no as variables

Step 3: Read data for 2 variables or initialize these 2 variables.

Step 4: Multiply two variables and store the result in mul_of_no variable.

Step 5: Print the multiplication 

Step 6: End

Example 2 – Calculate the area and perimeter of a rectangle

The algorithm to calculate the area and perimeter of a rectangle are as follows:

Step 1: Start

Step 2: Declare variables length, breadth, area, and perimeter

Step 3: Read the values for variables length, breadth from user

Step 4: Calculate the area of rectangle as length*breadth and perimeter as 2*(length + breadth)

Step 5: Print the result that is variables area and perimeter

Step 6: End

Example 3 – Calculate factorial of a number

The algorithm to calculate factorial of a number is as follows:

Step 1: Start

Step 2: Declare the variables no, factorial.

Step 3: Read the variable no from the user and initialize factorial variable to 1

Step 4: Multiple the factorial variable with n and store the result in factorial variable and decrement the variable n by 1.

Step 5: Repeat the step 4 until no becomes 1.

Step 6: Print the result that is print the factorial variable.

Step 7: Stop