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programming part 1 introduction to python.pptx
- 1. Prepared By hashini Danansuriya Programming .eg¨ úi£ug l %uf,aL,sùu Lesson 01 Grade 11 (part 1) 1
- 2. Prepared By hashini Danansuriya 1.1 Analyzing aproblem (.eg¨jla úYaf,aIKh lsÍu) 2 Processing Input Output Raw materials Result wdod k m %;sodk h ieliSu
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- 4. Prepared By hashini Danansuriya Exercise: 1. Identify theinputs, process and output related to dividing 100 toffees among 20 people 2. Identify the inputs, process and output in making a kite 4
- 5. Prepared By hashini Danansuriya Alternative solutions(úl,am úi÷ï y÷kd.ekSu) 5 Ifthere are more than one solution to a given problem, such solutions are called alternative solutions. .eg¨jla i|yd úi÷ï tllg jvd jeäfhka mj;S kï tajd úl,am úi÷ï f,i ye¢kafõ' All the solutions pertaining to a problem are called solution space. fufia .eg¨jlg mj;sk ish¨ úi÷ï" úi÷ï wjldYh f,I ye¢kafõ' In order to create a short, simple program the appropriate solution must be selected from the set of alternative solutions.
- 6. Prepared By hashini Danansuriya 1.2 Problem solvingusing Algorithms (.eg¨ úi£u i|yd we,af.dß;u f.dvke.Su) 6 An algorithm is a method(step by step procedure) to show the steps in solving a problem. .eg¨jla úi£u i|yd wkq.ukh lrkq ,nk mshjr oelaùfï l%uh we,af.dß;uhla f,i ye¢kafõ' Algorithms are needed to present a way to solve the problem with a plan. fuys wjYH;dj jkafka mQ¾j ie,iqula iys; j ksjerÈ j .eg¨jlg úi÷ula fiúh yels l%shdud¾.hla oelaùuhs' An algorithm is a complete step-by-step procedure for solving a problem or accomplishing a task
- 7. Prepared By hashini Danansuriya An Algorithm mustbe.. 7 Be Precise - Accurate Be Logical Be Effective Terminate Eventually
- 8. Prepared By hashini Danansuriya Algorithms in aprogram must: Obtain a correct solution within a finite time be clear, precise and unambiguous(not open to more than one interpretation) ; and be in a format which lends to an elegant implementation…in a programming language 8
- 9. Prepared By hashini Danansuriya Exercise: There are 183students in a primary school. The principal has decided to hold an inter-house sports meet dividing them into three houses – Olu, Nelum, Manel. Develop an algorithm to divide the students into three houses. 9
- 10. Prepared By hashini Danansuriya 1.2.1 Control Structures(md,k jHqy) 10 1.Sequence (wkql%uh) 2.Selection (jrKh) 3.Repetition (mqk¾lrKh)
- 11. Prepared By hashini Danansuriya Sequence wkql%uh 11 SEQUENCEis a linear progression where one task is performed sequentially after another… we,af.dß;uhl msysá mshjr lsysmhla fyda ish,a, u fyda wdrïNl mshjrlisg wjidk mshjr olajd by< isg my<g tfl,af,a wkqms<sfj<ska l%shd;aul ùu wkql%uh f,i ye¢kafõ' solution steps must follow each other in a logical sequence Statements are executed in the same order as they are written.
- 12. Prepared By hashini Danansuriya Sequence wkql%uh 12 Wake Up GetOut of Bed Have A Shower Dry Yourself Get Dressed Have Breakfast Pack Bag/Lunch Leave
- 13. Prepared By hashini Danansuriya Sequence wkql%uh 13 Certainevents must occur in a particular order for example, we should get out of bed before a shower Some events must occur prior to another event(s) for example, there is no drying yourself prior to a shower Some other events may occur in any order and do not affect the overall solution for example, we can pack bag before or after having breakfast Note:
- 14. Prepared By hashini Danansuriya 1) Input lengthand width of a rectangle and calculate the area and the perimeter. 2) Input area of the square and calculate the length. 3) Input the perimeter of a circle and calculate the area. Exercise: 14
- 15. Prepared By hashini Danansuriya Selection jrKh 15 SELECTION -there may be alternative steps that could be taken subject to a particular condition. we,af.dß;uhl we;=<;a fldkafoaishla ;Dma; ùu fyda fkdùu fyda wkqj l%shd;aul l< hq;= mshjr l=ula o hkak ;SrKh jk wjia:djla jrKhla f,I ye¢kafõ' Selection is a situation where steps are executed depending on whether a condition of an algorithm is satisfied or not. fuys § jrK folla mj;sk w;r fldkafoaish ;Dma; jkafka kï tla jrKhla o ;Dma; fkdjkafka kï wfkla jrKh o f;dard .efka'
- 16. Prepared By hashini Danansuriya Exercise: Page 8 –2nd question 16
- 17. Prepared By hashini Danansuriya Repetition / Iterationmqk¾lrKh 17 ITERATION - certain steps may need to be repeated while, or until, a certain condition is true we,af.dß;uhl we;=<;a mshjrla" mshjr lsysmhla fyda fldkafoaishla ;Dma; jk f;la fyda ;Dma; j mj;sk ;=re fyda kej; kej; isÿùu mqk¾lrKh f,I ye ¢kafõ' In programming we call it as a Loop If one or several steps of an algorithm are repeated until a condition is satisfied, it is called repetition.
- 18. Prepared By hashini Danansuriya Repetition mqk¾lrKh 18 Considerthe example of getting out of bed For the step --having a shower-- the following loop could be substituted; test cleanliness while I am dirty wash myself test cleanliness The loop continues until the condition of cleanliness changes
- 19. Prepared By hashini Danansuriya Representing an Algorithm we,af.dß;ubÈßm;a lsÍug úúO fuj,ï Ndú;h Flowcharts .e,Sï igyka Pseudo Codes jHdc fla; 19
- 20. Prepared By hashini Danansuriya Flowcharts 20 A flowchartis a step by step Diagrammatic representation of the program. we,af.dß;uh rEmuh wdldrfhka mshjfrka mshjr f.dv kef.k fyda f.dv ke.S we;s wdldrh fyda bÈßm;a lsÍu i|yd .e,Sï igyka fhdod .efka‘ Each type of task is represented by a symbol fuys§ tla tla l%shdj oelaùu i|yd my; oelafjk ixfla;
- 21. Prepared By hashini Danansuriya Flowcharts 21 Diagram Notation Representation OvalStart / End of a Program wdrïNh fyda wjidkh Parallelogram Input / Output of Data wdodkh fyda m%;sodkh Rectangle Processing Operation l%shdj,sh
- 22. Prepared By hashini Danansuriya Flowcharts 22 Diagram Notation Representation RhombusDecision Box ;SrKh Circle Connection iïnkaOlh Arrows Direction of Flow .e,Sï ÈYdj
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- 24. Prepared By hashini Danansuriya Start Stop Wake Up Get Outof Bed Have A Shower Have Breakfast Get Dressed Pack Bag/Lunch Leave Dry Yourself Example: 24
- 25. Prepared By hashini Danansuriya Exercise: Draw a flowchart to find the sum and average of two numbers 25
- 26. Prepared By hashini Danansuriya Start Input Number1 Input Number2 Sum = 0 Average= 0 Average = Sum / 2 Display Sum, Average Stop Sum = Numbe1 + Number2 26 Exercise
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- 28. Prepared By hashini Danansuriya 28 Stop Pack Bag/Lunch Leave Read aBook yes Have Breakfast Get Dressed Am I Hungry ? Is it a weekday ? yes Start Wake Up Get Out of Bed Have A Shower Am I Dirty? yes No No Dry Yourself No Example:
- 29. Prepared By hashini Danansuriya 29 Exercise: Draw a flowchartto input the length and width of a quadrilateral and state whether it is a square/ rectangle
- 30. Prepared By hashini Danansuriya 30 Start Input the angle magnitude Is angle= 90 Display “Figureis Square/ Stop Y N Display “Figure is rhombus/
- 31. Prepared By hashini Danansuriya 31 Exercise: Draw a flowchartto input the magnitude of angles of a quadrilateral and state whether it is a square or a rohmbus.
- 32. Prepared By hashini Danansuriya 32 Start Get Length Get Width Is Length equal Width ? Display “Figureis Square” Stop Y N Display “Figure is Rectangle”
- 33. Prepared By hashini Danansuriya 33 Repetition Draw a flowchartto find the sum of first fifty natural numbers Start SUM = 0 N = 0 N=N+1 SUM = SUM + N IS N = 50? PRINT SUM End
- 34. Prepared By hashini Danansuriya 34 Write down theoutput generated by the following flowchart. (Figure 1)
- 35. Prepared By hashini Danansuriya Pseudo codes jHdcfla; 35 An algorithm in simple English form is called Pseudo codes we,af.dß;uhla ir, bx.%Sis jpk fhdod f.k ,sÅ; j oelaùu jHdc fla; u.ska isÿ fõ' Can plan the program. Can use pseudo code to describe the program to non-technical user. Can provide guidelines to a programmer to write the program. Opportunity to detect any logic error prior to actual coding. Advantages of Pseudo Codes
- 36. Prepared By hashini Danansuriya 36 BEGIN – Toindicate a beginning wdrïNh END – To indicate an end wjidkh INPUT, READ, GET – To indicate an input wdodkh OUTPUT, DISPLAY, SHOW – To show an output m %;sodkh PROCESS, CALCULATE – To indicate a process l%shdj,sh IF … THEN … ELSE … ENDIF – Used to indicate a selection jrKh FOR – DO WHILE – ENDWHILE Used to indicate a repetition REPEAT – UNTIL mqk¾lrKh
- 37. Prepared By hashini Danansuriya Sequence wkql%uh 37 • Ina sequence control structure, statements are executed in the same order as they are written. Pseudocode; statement 1 statement 2 statement 3 • This sequence control structure can be used to represent four basic computer operations: receive & output information, perform arithmetic, and assign values Statement 1 Statement 3 Statement 2 START STOP
- 38. Prepared By hashini Danansuriya 38 Exercise Write apseudo code that inputs two numbers (a and b) and calculates the sum of the numbers and output the sum
- 39. Prepared By hashini Danansuriya 39 BEGIN INPUT a INPUT b sum= a + b OUTPUT sum END
- 40. Prepared By hashini Danansuriya Selection jrKh 40 Compareand Select One of Two Alternative Actions Select one path according to the condition ◦ IF …. THEN If the condition is true do the statements inside IF No operation if the condition is false ◦ IF …. THEN …. ELSE If the condition is true do the statements inside IF If the condition is false do the statements inside ELSE
- 41. Prepared By hashini Danansuriya 41 IF condition THEN sequence- 1(statements) ELSE sequence- 2(statements) ENDIF Pseudocode: IF Condition? Statement sequence1 ENDIF Statement sequence 2 False True Flow chart:
- 42. Prepared By hashini Danansuriya 42 IF <condition> THEN sequence1 ENDIF IF <condition> THEN sequence 1 ELSE sequence 2 ENDIF Example1: IF a>0 THEN Print a END IF Example2: IF a>b THEN Print a ELSE Print b END IF
- 43. Prepared By hashini Danansuriya 43 Exercise: Write a pseudocode that inputs two numbers (a and b) and output the largest number.
- 44. Prepared By hashini Danansuriya 44 BEGIN INPUT a INPUT b IFa < b THEN OUTPUT b ELSE OUTPUT a END IF END
- 45. Prepared By hashini Danansuriya Repetition mqk¾lrK 45 Samesequence of operations need to be repeated Use ◦ WHILE … ENDWHILE ◦ DO WHILE … ENDDO ◦ FOR … ENDFOR
- 46. Prepared By hashini Danansuriya 46 While Loop Pseudocode: WHILE<Condition> Statement- Sequence END WHILE While Condition ? Statement sequence true false EndWhile
- 47. Prepared By hashini Danansuriya 47 Exercise: Write a pseudocode that inputs ten numbers and outputs the sum and average of them.
- 48. Prepared By hashini Danansuriya 48 BEGIN count = 1 sum= 0 WHILE count <= 10 INPUT a sum = sum + a count = count + 1 END WHILE average = sum / 10 OUTPUT sum, average END
- 49. Prepared By hashini Danansuriya 49 Exercise: Write a pseudocode that inputs ten numbers and outputs the sum and average of them.
- 50. Prepared By hashini Danansuriya 50 BEGIN count = 0 sum= 0 DO INPUT a sum = sum + a count = count + 1 WHILE count < 10 average = sum / count OUTPUT sum, average END
- 51. Prepared By hashini Danansuriya 51 The following isa part of a pseudo code which is used to evaluate the final grade achieved by a student in an examination, based on the average marks obtained for two subjects. Set Average to 0 Get Name Get marks for Subject1 Get marks for Subject2 Average = (Subject1 + Subject2)/2 IF (Average) >= 50 display Name, “Pass” ELSE display Name, “Fail” Ends if The name and the marks for the subject are as follows. Write the output of the above pseudo code for each of the student.
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