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Software Life Cycle

What. How. Do it. Test. Use. Software Life Cycle. Requirements Gathering, Problem definition. Analysis and Design (Programming techniques). Coding. Testing. Implementation and Maintenance. Write Program. Errors. Compile Program. Correct Errors. Run and Test Program. Errors.

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Software Life Cycle

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  1. What How Do it Test Use Software Life Cycle Requirements Gathering, Problem definition Analysis and Design (Programming techniques) Coding Testing Implementation and Maintenance

  2. Write Program Errors Compile Program Correct Errors Run and Test Program Errors Correct Errors Errors Submit Program Correct Errors Success Coding and Testing

  3. How to develop a program • Identify the steps and execution sequence. • Every program consist of mainly three parts: Input, Processing and Output Example: Add two numbers Steps • Read/Input two numbers • Add these two numbers • Display/Output the result of addition • Algorithm : Steps written in English language. • Program : Algorithm written in a specific high level language.

  4. Algorithm • An Algorithm is a solution to a problem that is independent of any programming language. • An Algorithm is • a finite sequence of steps • each step shall be clearly stated and understandable • for each input, it shall terminate in finite time with output How we solve the problem with Computer?

  5. Program and Programming • Program: • A set of instruction written in a programming language that a computer can execute so that the machine acts in a predetermined way. • Program solves a problem • Before writing a program: • Have a thorough understanding of the problem • Carefully plan an approach for solving it. • Programming: • The Process of providing instructions to the computer that tells the processor what to do.

  6. Algorithms & Programs • An Algorithm is a solution to a problem that is independent of any programming language.While • A program is an algorithm expressed using a specific set of instructions from any programming language.

  7. Algorithm Example • Maximum of two numbers • Steps: • Read/input two numbers • Compare two numbers • Print the Greater number • Average of three numbers • Steps: • Read/input three numbers • Add three numbers • divide the sum by 3. • Print the result of divison

  8. Pseudocode • This is a common notation for writing algorithms. • Mixture of English language statement and a programming language( like C) code. • It is an intermediate step in writing a program. • Not actually executed on computers. • Standard mathematical notations like exponents,square-root symbols etc. are allowed in pseudocode.

  9. Rules for pseudo code • The beginning and end of a pseudo code is marked with keywords START and STOP. • Every variable should be initialized in the beginning only using INITAILZE • Values from user should be accepted using keyword READ, and should be display using WRITE. • All “alphanumeric” values should be enclosed in single or double quotes. • All the nested loops are: for-do-done, while-do-done • All the control structures are: if-then-else-fi, switch-case.

  10. Examples Pseudo code to find out the sum of all odd numbers in the range 1 to 10. START INITIALIZE a[10], sum=0,i for i=1 to 10 do Read a[i]; if (condition) then Calculate sum=sum+a[i]; done Write sum; STOP

  11. Examples Pseudo code to find out the maximum number from 20 given numbers. START INITIALIZE a[20],max,i; for i=1 to 20 do Read a[i]; done max=a[1]; for i=2 to 20 do if a[i]>max then Assign max=a[i]; done Write max; STOP

  12. Practice Example Write an algorithm for the given problem: 10 students of a class appears for a test in three subjects. Each test is out of 100 marks. The percentage of each student has to be calculated and depending on the percentage calculated, grades are given below:

  13. Flowchart • Graphical representation of an algorithm • Components: • Arrows/lines :Flow of control • Parallelogram: Indicates input and output operations • Rectangle symbol (action symbol): Indicates any type of action/computational step • Oval symbol:Indicates the beginning or end of a program or a section of code • Diamond: Decision

  14. Flowchart Notations Arrows Diamond Parallelogram Oval Rectangle

  15. READ A,B START C=A+B PRINT C STOP Example: Add two Numbers

  16. Draw both flow chart and pseudo code You are required to calculate area of circle and rectangle. Accept from user the figure and then accordingly calculate and display.

  17. Pseudo code START INITIALIZEFIG, area=0; READ FIG ; IF FIG = “circle” CALL CIR_ROUTINE ; ELSE IF FIG=“rectangle” CALLRECT_ROUTINE ; ELSE GOTOlabel 1; ENDIF ENDIF WRITE“ area of figure”, area; STOP label 1:

  18. CIR_ROUTINE INITIALIZE radius=0; READ radius; CALCULATE area = 3.14 * radius * radius; RETURN to Calling procedure RECT_ROUTINE INITIALIZE length=0, width=0; READ length,width; CALCULATE area = length*width; RETURN to Calling procedure

  19. Flow Chart READ FIG START FIG? READ LENGTH & WIDTH other rectangle circle READ RADIUS AREA=LENGTH * WIDTH PRINT AREA AREA=3.14*RADIUS * RADIUS STOP

  20. Problems • GCD of three numbers • Calculate 2n • Roots of equation ax2+bx+c=0 • Largest of N numbers • Generate the fibonacci series

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