Programs - programming language:

Programs to implement algorithms on the computer must be written in a language that the computer can understand. It is fruitful, therefore, to describe algorithms in a language that resembles the language used to write computer programs.  This is called pseudo code.  It is not a programming language with a rigid syntax, but is similar to one.  The idea is that it should be easy to write a program by looking at the pseudo code.  

Let us take few problems to illustrate how to express the solution to a problem in the form of an algorithm. We will also see how algorithm can be diagrammatically represented using flow chart, and also how a program can be written based on the algorithm.  For providing a solution to any problem some input from the user is required. In the following examples the number n that is expected from the user should be an  integer. In the program, it will be declared of the required type only, referred as data type of the variable. A Detailed description of variable and data type is given in a later section.