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Introduction to Programming

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Agenda

  • How does computing happen in a computer?
  • High-level Languages (HLL)
  • Introduction to C Language
  • Lifecycle of a C Program

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HOW DOES COMPUTING HAPPEN?

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Computing - Under the Hood

  • CPU
    • The workhorse under the hood of any computer
    • Carries out instructions given in a program
  • Memory
    • The place where data created and used by CPU is stored
  • Input Device
    • Used for providing inputs of the program
  • Output Device
    • Used for showing output of the program

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It is all binary!

  • Instructions to CPU are expressed and understood ONLY IN BINARY (as a sequence of zeros and ones)
  • Data is stored and manipulated ONLY IN BINARY!

​

But….

Humans do not speak BINARY!

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HIGH-LEVEL PROGRAMMING LANGUAGES

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High Level Languages (HLL)

  • HLLs are languages that are used to give instructions to the computer by programmers
  • HLLs are written using normal alphabet of the English language
  • The language contains keywords that resemble some words from our natural language (e.g., for, do, while, if, etc.)

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Some Popular High Level Languages

  • C language
    • One of the most popular programming languages
    • Used widely in high-performance systems like embedded systems, microcontrollers, etc
  • Java
    • Very popular language for developing enterprise software applications
  • Python
    • Powerful language used widely in AI and ML applications

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Classes of Languages

  • Compiled languages
    • Compilation required to convert from high level to machine language
    • C, C++, Java, etc
  • Scripting languages (interpreted)
    • Compilation NOT required; an interpreter conveys appropriate instructions to the CPU dynamically
    • Python, shell script, etc.

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LIFE CYCLE OF A C PROGRAM

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Life Cycle of a C Program

HLL Instructions

Compile

Link

Execute

Programmer

Compiler

Linker

Operating System

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Compilation

    • Whether program is written as per proper grammar and punctuation!

Syntax checking

    • The object file contains machine language instructions in binary

Conversion to object file

    • A program that takes a high level program as input and give object file as output

Compiler

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Linking

Re-use

Writing a program that is self-contained for doing EVERYTHING is tedious

Programmers use pre-created “libraries” for implementing routing tasks

Linking

Linking is the process of integrating external programs that provide these reusable functions

A LINKER takes a set of object files as input and produces an executable as output

Execution

The operating system can now execute the “executable file”

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Summary

Life Cycle

HLL Instructions

Compile

Link

Execute

Programmer

Compiler

Linker

Operating System

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WHAT WE WILL EXPLORE

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About the C Language

  • C language was created in early 1970s specifically for writing the code for Unix Operating System
  • C language is a compiled programming language
  • C language is considered to be highly portable because compilers are available for almost every hardware and processor architecture

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Very Powerful Features

  • Provides very high performance
  • Provides great flexibility for system-level operations
    • Memory access via pointers
    • Storage / Disk access via system calls
    • Network programming via sockets
    • Inter-process communication via PIPES