By John, Kunal, Murid, Zamir. Turing Guide Repetition

Transcription

1 By John, Kunal, Murid, Zamir. Turing Guide Repetition

2 Table of Contents Title Page.1 Table of Contents...2 A Brief History of Turing. 3 What is Repetition.. 4 Infinite Loops...5 Conditional Loops Counted Loops Exiting Loops..8 Examples of repetition Repetition Review Repetition Test 17 Glossary...18 Credits

3 A Brief History of Turing Turing, a Pascal-like programming language, was developed in 1982 by University of Toronto students Ric Holt and James Purdy. Turing was named after a British scientist Alan Turing. Turing is taught as a warm-up program for students interested in learning Java in the future. There are two other versions of Turing,t Object-Oriented Turing and Turing Plus. In September 2001 the original Turing was renamed Classic Turing. Turing is not updated by Holt Software any more since the company went bankrupt with the decline in computer science classes. It is also only compatible with Microsoft Windows. Turing is used a lot in high schools in Ontario for students as an introduction to programming. Turing became free of charge for personal, commercial and education use on November 28, Ric Holt, Co-owner/creator of Turing.

4 What is repetition? Repetition is a function in the Turing software. The main function in repetition is the use of s There are four types of s: 1. Infinite Loops 2. Conditional s 3. Counted s 4. exiting s A good example of repetition is a clock. A clock moves in a circle from right to left and it repeats this circle over and over.

5 Infinite Loops In Turing there are four different types of s. There are Infinite, Conditional, Counted and Exiting s. Infinite Loops repeat themselves over and over again. The following code is an example of an Infinite. % The "ManyCircleAreas" program % Computes the areas of circles var radius, area : real const pi := put "Enter radius ".. get radius area := pi * radius ** 2 put "Area is ", area end. *Taken from Introduction to Programming in Turing by J. N. P. Hume Conditional Loops The second type of is Conditional. They are s that execute again and again if a given condition holds true. Conditional Loops are helpful for developing logic and if programs didn t consist of conditional s then programming codes would be much longer. Run the following example to see what happens. % The "ManyCircleAreas2" program % Compute circle areas until you enter a negative radius var radius, area : real const pi := put "Enter a negative radius to stop execution" put "Enter radius ".. get radius exit when radius < 0 area := pi * radius ** 2 put "Area is ", area end put "That's all folks" *Taken from Introduction to Programming in Turing by J. N. P. Hume In this program there is an exit when (refer to glossary) statement which checks to see if the statement inside the is true. If the statement is false then the

6 program will not run until its value is true. When the statement is true the computer leaves the to go to the statement after the end (refer to glossary). Once the computer executes the statement after the end it will stop the program. There are different types of exit when statements a user can use in his or her program that involves comparing two operators. They are called Logical, Boolean, or true/false statements. These are the complete set of different operators. = equal to < less than > greater than not= not equal to <= less than or equal >= greater than or equal *Taken from Introduction to Programming in Turing by J. N. P. Hume Counted Loops The third type of is a Counted Loop. Counted Loops repeat for a fixed number of times. A Counted starts with the keyword for (refer to glossary about for ) followed by the word count, which is an index or counter (refer to glossary) in the. The index in a is a variable called integer (refer to glossary) which is a special property that is declared in a for statement. Run the following example. % The "ComputeAverages" program % Reads marks and computes average var mark : int var sum : int := 0 put "Enter marks" for count : put count get mark sum := sum + mark end for put "Average is ", round (sum / 5) *Taken from Introduction to Programming in Turing by J. N. P. Hume In this program that reads marks int is given the value 1 the first time the is executed and goes on until it reaches 5. Another way to assign the value of int is to write This gives the start trough the end value. You cannot use this type of counter outside a because count would not be available under the end for (refer to glossary) statement. In the execution screen when the users enter the marks they are read by the get

7 (refer to glossary) statement and counter value is assigned on each line. If the user decides to enter all his or her marks on one line then the execution screen would be like this. *Note: get statement does not read all marks until they are entered. Enter 5 marks Average is 73 *Taken from Introduction to Programming in Turing by J. N. P. Hume When writing program codes that use for statements it is recommended not to use the number 5. If you use 5 then you should declare a constant such as nummarks. This means the code would be different. % The "ComputeAverages" program % Reads marks and computes average var mark : int var sum : int := 0 const nummarks := 5 put "Enter", nummarks, marks for i: 1.. nummarks put count get mark sum := sum + mark end for put "Average is ", round (sum / nummarks) *Taken from Introduction to Programming in Turing by J. N. P. Hume If you wanted to make other modifications to this program you could change anything you like. If you were to increase the index in The Compute Averages" program then you would have to use by clause (refer to glossary). This clause will increase any value greater then 1. Run this example that has a by clause. for count : by 2 *Taken put count from Introduction to Programming in Turing by J. N. P. Hume end for In the above program the index increases by 2 but if the value is greater then 10 then the will exit it self. When using for decreasing (refer to glossary) in counted s you are counting backwards. Use for decreasing when counting backwards. Example program that counts backward.

8 for decreasing count: body of... end for Exiting A Loop In order to exit a you will have to use an exit when statement. This helps the user exit the when he or she is done inputting values. For more information about any type of s please refer to the glossary. Examples of Repetition and Their Results This page will show several examples of repetition questions and their answers. Hopefully, these examples will help you better understand repetition.

9 1. Positive integers are to be gathered from the keyboard. When a nonpositive integer is encountered, the count and sum of all the positive integers is to be displayed. Write a simple program to accomplish this task. var integer : int var sumofinteger : int integercount := integercount + 1 end if var integercount : int integercount := 0 sumofinteger := 0 end exit when integer <= 0 put "Enter any random integer?".. get integer if integer > 0 then put skip, "The sum of the integers is : ", sumofinteger put skip, "The Total number of positive integers is : ", integercount sumofinteger := sumofinteger + integer 2. Gather a set of marks, and display their mean. var mark : real var count : int var mean : real

10 var sum : real count := 0 sum := 0 else mean := 0 end if put skip, "Count : ", count put "Mean : ", mean :0:1 put "Mark?".. get mark exit when mark < 0 sum := sum + mark count := count + 1 end if count not = 0 then mean := sum/count 3. Display the integers from 0 to 13. var integer : int integer := 0 put "These are the following integers from 0-13"..

11 put skip, 0 integer := integer + 1 delay(1000) exit when integer >=13 end put skip, "Those are the integers from zero to 13".. put skip, integer.. 4. Gather an integer, and display its time-tables from 0 to 13. var integer : int var product : int put "Enter an integer from 1-13 ".. get integer product := integer * 1 product := integer * 2 product := integer * 3 product := integer * 4 product := integer * 5 product := integer * 6 product := integer * 7 product :=integer * 8 product := integer * 9 product := integer * 10 product := integer * 11 product := integer * 12 product := integer * 13

12 exit when product = integer *13 end. 5. Display the numbers 1 to 15, each in a different colour. var colournumber : int colournumber := 0 colour (colournumber) put "This is the colour", colournumber exit when colournumber >= 15 colournumber := colournumber + 1 delay (1000) end 6. Gather the user s name and display a never ending amount of Greeting followed by the user s name. var fullname : string put "What is your full name? "

13 get fullname put "Greetings,", fullname end 7. Display a user-specified character in a never-ending pattern of diagonals. const DELAY := 100 var row : int var column : int var character : string var rowchange : int var columnchange : int row := 1 column := 1 columnchange := 1 rowchange := 1 put "Enter any character" get character cls 8. var rowsleft := 80 var columnleft := 25 var rows := 1 locate (row, column) put character.. delay (DELAY) row := row + rowchange column := column + columnchange if row <= 1 or row >= maxrow then rowchange := - rowchange end if if column <= 1 or column >= maxcol then columnchange := - columnchange end if end var columns := 1 var character : char put "Enter any Character "

14 get character cls for j : for decreasing i : rowsleft.. j colourback (blue) delay (20) locate (columnleft, i) for i : j.. rowsleft put character.. colourback (blue) delay (20) end for put character.. end for for i : j.. columnleft colourback (blue) delay (20) locate (i, rowsleft) put character.. for decreasing i : columnleft.. j colourback (blue) delay (20) locate (i, j) put character.. end for columnleft := columnleft - 1 rowsleft := rowsleft - 1 end for end for

15 Repetition Review Complete the following exercises: 1. Display all the numbers from with a 1-second delay. 2. Get a name and display a birthday message with the name entered. Repeat until asked to stop. 3. Display the message This is a 20 times and finish with Done! on a clear screen 4. Get a name and display a greeting message and an option to repeat or exit the program. 5. Display all the numbers from in different colours. Answers: const LIMIT := 255 const DELAY := 1000 var i : int i := 1 put i delay (DELAY) i := i+1 exit when i > LIMIT end const STOP := "stop" var fullname : string put "Enter your full name: " get fullname : * cls exit when fullname = "stop" put "Happy Birthday ", fullname, ", enter a friends' name or type 'stop' to stop the program" end const LIMIT := 255 const DELAY := 1500 var i : int i := colour(i) put i delay (400) i := i-1 exit when i > LIMIT end const LIMIT := 20 const DELAY := 400 var i : int i := 1 delay (DELAY) i := i+1 put "This is a " exit when i > LIMIT end cls put "Done!" const STOP := "stop" var fullname : string put "Enter your full name: " get fullname : * cls put "Hello ", fullname, ", enter a friends' name or type 'stop' to stop the program" exit when fullname = "stop" end

16 Repetition Quiz 1. Display the even numbers from 1-24 with a 1/2 second delay. 2. Recreate this pattern Get a name and repeat it 20 times in different colours. const LIMIT := 24 const DELAY := 500 var i : int i := 2 put i delay (400) i := i+2 exit when i > LIMIT end const DELAY := 1000 var i : string i := "1" put i delay (DELAY) i := i+"1" exit when i > "111111" end var name : string var i : int put "Enter your name: ".. get name i := 1 i := i+1 colour (i) put name exit when i > 20 end

17 Glossary Loop: Repeats itself over and over until told to stop. Exit When: Statement used to exit the when told so. End Loop: Statement that is used to stop the. For Loop: executes a program a specified number of times. Count: Adds one to the amount of numbers Index: Index in Turing is a variable called integer Counter: Tells the program what number to begin at. Integer: Just a number a user/programmer use in some assignments. End For: Ends the for Get: Gets what the user puts in to the program and follows the programmers instructions. By: Tells the user to increase a value. For increasing/ decreasing: Depending on the programmer the integer will either increase or decrease.

18 Credits John: Examples of Repetition Kunal: Repetition Review, Repetition Test, Editing Murid: Cover, Table of Contents, Glossary, History of Turing Zamir: Loops Special Thanks to Mr. Arkin for some of the examples used in this book And J.N.P. Hume for his guide to Turing.