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History of Programming

  • What is a program?
  • Programming 200 years back v/s Programming in a versatile modern computer in the 21st century
  • Key milestones in digital computing after invention of Colossus Mark I:
    • 1943: Colossus Mark I, the world's first programmable electronic digital computer, is built in the UK to help with code-breaking during World War II.
    • 1945: The Electronic Numerical Integrator and Computer (ENIAC) is built in the US by John Mauchly and J. Presper Eckert. It's the first general-purpose electronic computer.
    • 1949: The Manchester Mark 1 is built in the UK, which is the first computer to have a stored-program architecture.
    • 1951: The UNIVAC I (Universal Automatic Computer I) is built in the US, which is the first computer to be produced in quantity and sold commercially.
    • 1957: The FORTRAN (FORmula TRANslation) programming language is developed by John Backus and his team at IBM.
    • 1964: IBM introduces the System/360 mainframe computer, which allows customers to upgrade from smaller systems to larger ones without having to rewrite their software.
    • 1969: The ARPANET, the precursor to the modern internet, is created by the US Department of Defense's Advanced Research Projects Agency (ARPA).
    • 1971: Intel introduces the first microprocessor, the Intel 4004, which is a single-chip CPU designed for use in calculators.
    • 1972: Intel introduces the 8008, an 8-bit microprocessor that was the predecessor to the 8080 and the 8085.
    • 1974: Intel introduces the 8080, an 8-bit microprocessor that was widely used in early personal computers.
    • 1976: Intel introduces the 8085, an improved version of the 8080 with more features and better performance.
    • 1976: Apple Computer is founded by Steve Jobs and Steve Wozniak and releases the Apple I personal computer kit.
    • 1978: Intel introduces the 8086, a 16-bit microprocessor that was the first in the x86 family of processors and the basis for the IBM PC.
    • 1981: IBM introduces the IBM PC, which becomes the dominant platform for personal computing in the 1980s and 1990s, which uses the 8088, a variant of the 8086 with an 8-bit external bus.
    • 1984: Apple introduces the Macintosh personal computer, which features a graphical user interface and a mouse.
    • 1985: Intel introduces the 80386, a 32-bit processor that greatly improved the performance of personal computers.
    • 1991: The World Wide Web is introduced by Tim Berners-Lee, a computer scientist at CERN in Switzerland.
    • 1993: The Pentium processor is introduced by Intel, which becomes one of the most successful microprocessors in history.
    • 2001: Apple introduces the iPod portable media player, which revolutionizes the music industry.
    • 2006: Intel introduces the Core microarchitecture, which greatly improves the performance and power efficiency of its processors.
    • 2007: Apple introduces the iPhone smartphone, which revolutionizes the mobile phone industry.
    • 2010: Apple introduces the iPad tablet computer, which revolutionizes the tablet market.
    • 2011: IBM's Watson computer defeats two human champions on the quiz show Jeopardy!, demonstrating the power of artificial intelligence and natural language processing.
  • Why we need a programming language: ambiguity of human languages

Introduction to Python 3

  • Hello World in Python interactive shell mode/IDLE

    >>> print("Hello World")

  • Programming in Python 3: a rudimentary functional approach

    >>> # Program: actual.py
>>> # A simple program illustrating Python tokens
>>> # This is a single line comment
>>> 
>>> # Prints to console/terminal
>>> print("Hi, this is my first actual program in Python 3")
>>> 
>>> # input(): Prints the argument string and waits for user input and a LINEFEED
>>> # The user input until just before the LINEFEED is 
>>> # stored as a 'string' in a newly created 'variable' x
>>> x = input("Enter your name: ")
>>> 
>>> # Prints "Woah, ", then the string stored in x, then
>>> # " is a beautiful name!"
>>> print("Woah, " + x + " is a beautiful name!")
>>> 
>>> # End of actual.py

📝 Programs to try:

  1. Write a program in the interactive shell to input the name and age of the user and print the corresponsing information as a formatted string:

    'Hello, {name}! You are {age} years old'

  2. Write a program in the interactive shell to input a string and print its length as a formatted string: 'x is {length} characters long'. (Hint: use function len() with the string variable as its argument.)

Algorithmic Intuition: Thinking Discrete like a Computer

  • Think: "find the sum of my number and 20, and say the result out loud"

  • A program to add a given number 45 to an input number

    >>> # Program: sum.py
>>> # A simple program to add 45 to a number
>>> 
>>> x = input("Enter a number: ")
>>> x = int(x)
>>> x = x + 45
>>> 
>>> print("45 added to the number is " + str(x))

(What are Python datatypes?)

📝 Programs to try:

  1. Take the above example of the program and modify the output to print:

    '{input_number} + 45 = {x}'

    INSTEAD OF:

    '45 added to the number is {x}'

    Notice, other than in the print(...) statement, what other changes are necessary.

  2. Write a program in interactive shell to input three numbers and print their sum formatted as:

    '{number1} + {number2} + {number3} = {sum}'

Defining our own functions

  • A function is a block of code which only runs when it is 'called'. You can pass data, known as parameters or arguments, into a function. A function can return data as a result, or return nothing.

    • Example 1

      >>> def greet(x):
...     print("Hello, " + x + "!")
... 
>>> greet("Bill")
>>> greet("Steve")

    • Example 2

       >>> def printsum(x, y):
 ...     s = x + y
 ...     print("The sum of " + str(x) + " and " + str(y) + " is " + str(s))
 ... 
 >>> def getsum(x, y):
 ...     s = x + y
 ...     return s
 ... 
 >>> printsum(3, 77)
 >>> getsum(45, 32)

📝 Programs to try:

  1. Write two functions getprod(x, y) and printprod(x, y) in the same fashion as above and call them in main. Acknowledge the distinction between a function that 'returns' a result and one that doesn't.

  2. Write to program to input the name of a character to 'kill' and the number of bullets required to do so. Write a function kill(n, b) that takes two parameters as input: n (the name of the character to kill), and b (the number of bullets) and make it print the following message to the console:

    '{n} was killed with {b} bullets :P'