Basics of C Programming

⯈Basic C Programs

Algorithm and its characteristics

An Algorithm is a step-by-step procedure to solve a given problem, which has the following characteristics.

  1. Input: An algorithm should have zero or more inputs.
  2. Output: An algorithm should have at least one output.
  3. Finiteness: An algorithm should have finite number of steps. The algorithm shouldn’t go on repeating for infinite time. If an algorithm runs for an infinite time then we may not get the output, which may fail the 2nd characteristic (output).
  4. Definiteness: Each step of the algorithm should be clear and precise. There shouldn’t be any ambiguity in carrying out the steps of the algorithm. 
  5. Effectiveness: Each step of the algorithm should terminate in finite amount of time. The algorithm may have finite steps, but say for example the step 2, takes infinite time to complete, the algorithm will never reach to step 3.

There are some algorithms where we have zero inputs, like calculating the value of PI, accurate to 4 decimal places. 

An algorithm should produce at least one output, if an algorithm doesn’t provide any output, then there was no point in solving the algorithm.

Writing an algorithm:

The algorithm should be written in a step-by-step manner. It can be written in a language near to the programming language so that the translation from algorithm to program will be easy.

We will write the algorithm using the:

  1. Name of algorithm: says what does the underlying algorithm perform. 
  2. Step number: which indicates what step we are carrying out.
  3. Explanatory comments: which says what does the following step will perform. These are written in square brackets. These are optional. 

Example: Write an Algorithm to add two numbers.

Algorithm Name: Algorithm to add two numbers.

Step 1: Start

Step 2: Read two numbers as A and B.

Step 3: Sum = A+B [Adding two numbers]

Step 4: Display Sum.

Step 5: Stop [or End].

We will discuss in the next sections after introduction to  flowchart on how we write the algorithms using the above steps.

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