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Unit II: Introduction to Python


                                                          GETTING STARTED WITH
                     2                                   PYTHON PROGRAMMING














          Chapter Outline


          2.1 Why Python?                                    2.2 Features of the Python programming language
          2.3 Shortcomings of Python                         2.4 Downloading and Installing Python
          2.5 Using the Python IDLE                          2.6 Exiting Python IDE







        Introduction

        We already know that a computer program is a finite sequence of instructions for a computer to perform a task. A
        program may be written in a low-level programming language such as machine language and assembly language or
        a high-level programming language such as BASIC, COBOL, C, C++, JAVA, Python. As programs written in high-level
        languages are easy to write and comprehend, most programs are written in high-level languages. A program written in
        a high-level programming language is called the source code. As a computer only understands binary language—the
        language of 0's and 1', the source code must be transformed into a program in the machine language of the computer
        (expressed in 0's and 1's) with the help of an interpreter or a compiler. A program in the computer's machine language
        is called the object code or binary code.
        In the case of a compiled language such as Pascal, C, and C++, the compiler converts an entire program (source code)
        into machine language code (object code/ binary code) in one go. The compiler reports all the errors/ warnings to the
        programmer. The programmer rectifies the errors and re-compiles the program. If errors still remain, they also need
        to be corrected. When the program becomes error-free, the compiler generates the object code that can be executed
        to produce the results. On the other hand, in the case of an interpreted language such as Python, Perl, and PHP, the
        interpreter processes the source code in small chunks, often one statement at a time, generating the machine code and
        executing it. If an error is encountered in a statement, it has to be rectified before the interpreter can proceed further.



                 In which environments is a compiler preferable over an interpreter and vice versa?



        Python  is  a  programming  language  developed  by  Guido  Van  Rossum  in  1991  at  the  National  Research  Institute
        for Mathematics and Computer Science, the Netherlands. Over the years, it has become one of the most popular
        programming languages. In this book, we will study Python programming to solve problems. To begin with, in this
        chapter, we will learn how to install Python on your desktop.

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