Introduction To Programming

Introduction to Programming Mehul Jain

Mumbai darshan again on th 16 july

Overview • • • •

Computer Systems: The Basics Algorithms Flowcharts Programs

Computer Systems • Dumb machines that only process instructions (programs) • Follow Garbage In Garbage Out (GIGO) principle • Can’t differentiate into correct/incorrect logic • Problem solving tool

Under the hood • Input: e.g.., Keyboard and Mouse • Processor: Central Processing Unit • Output: Monitor or a Printer

Algorithms • An Algorithm is a solution to a problem that is independent of any programming language. • Steps are essentially sequential in nature • All Inputs and Outputs have to be specified explicitly • Have a start state and an end state (explicit start and end points) • For each input, a result should be generated and that too in finite time

Use of algorithms • • • •

Facilitates easy development of programs Iterative refinement Easy to convert it to a program Review is easier

Q Write an Algorithm to solve quadratic equation (ax2 + bx +c =0) for Real Roots •

0. START

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Read a, b and c //(non zero constants) (Input)

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Disc=b2-4ac //Calc. Discriminant (Process)

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If Disc>=0 Then Goto step 5 Else Goto step 7 //For Real Roots (Decision)

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X1= (-b+√Disc)/2a, X2= (-b-√Disc)/2a //Calculating Roots (Process)

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Write X1 and X2

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STOP

FLOWCHARTS: A PICTURE IS WORTH A THOUSAND WORDS • A flowchart is a diagrammatic representation of an algorithm • Normally the “flow” of control is from top to bottom

Q Draw a flowchart for the algorithm of the prev. example (quad. eqn)

START Read a, b & c

Disc=b2-4ac No

Disc>=0 Yes

X1= (-b+√Disc)/2a, X2= (-b-√Disc)/2a

Write X1 and X2 STOP

PROGRAM • A program is an algorithm expressed in a programming language • Each language has a certain syntax and has a variety of programming constructs available for easier problem solving • “Perfectly Optimal Code” is a Holy Grail that has not many takers (abstraction v/s user friendliness)

CONSTANTS & VARIABLES

2007 NMIMS

• A constant is a constant is a constant • 23, 44, “NMIMS”, 65, “Hello”, a. • A Variable is a Container for Constants • Variables can change values during the execution of the program • e.g. a, num1,x

Arrays n

A(1)

A(n)

• An array is a set of identical variables that contain similar data • Arrays have a fixed size • Index numbers are used to access the Array variables