3 Project SummaryThis project named “Control Structure” is mainly focused on the working principle of various control Structures in VB and their implementation in Programming.Various Practical Examples have been included in this project relating to real life problems for the better understanding of the concepts.Programming questions, Output related questions are formed so as to improve the logical & problem solving ability of the students.
4 Learning ObjectivesWorking principles of various types of control structures in VB.Syntax & semantics of various statements in VB.Implementation of Control structures in Programming.Connecting real-world entities using control structures.Solving real-life problems using control structures.Enhancement of Logical & Problem solving ability of the learner.
5 Assessment Procedures Students performance will be judged/assessed by inspecting the following factors :Logic in Programming.Efficiency & Effectiveness of Programs.Usage of various control structures.Correct syntax.Correct code.Following stylistic guidelines while programming i.e. object naming conventions, meaningful object names, proper indentation & spacing, prettyprinting style etc.
6 Implementation Procedures Students will be explained about the working principle of individual statement with the help of its proper syntax and example.After explaining working principle of every statement, students will be given Practical Examples, implemented using VB language on Computer.Students will be demonstrated the usage and working of every statement in variety of ways, according to the options available in the syntax.
7 Implementation Procedures Students will be given practical questions to solve and implement using VB language.After implementing every type of control structure, students will be given a Home Assignment based on the statements studied.Students will be given a consolidated Assignment in the end of the chapter so as to test the logical ability of the children and their understanding about the different types of control structures and their implementation.
8 Resources UsedI am in teaching profession from last 12 years so this complete lesson plan, assessment procedure, programming questions, output related questions etc., are formed with my previous experience and knowledge. Still I would like to mention few resources I have used for the preparation of this Project :Text book of Informatics Practices by Sumita Arora.Previous year CBSE Board question papers.Computer.
9 Created By : Sudhir Kataria PGT Computer Sc. K V Chamera II VB Control StructuresCreated By : Sudhir KatariaPGT Computer Sc.K V Chamera II
10 Control FlowIn a program, statements may be executed sequentially, selectively or iteratively. Every programming language provides constructs to support sequence, selection or iteration. So there are three types of programming constructs :Sequential ConstructsSelection ConstructsIterative Constructs
11 Sequential ConstructThe sequential construct means the statements are being executed sequentially. This represents the default flow of statements.Stament 1Stament 2Stament 3
12 Selection ConstructThe selection construct means the execution of statement(s) depending upon the condition-test. If a condition evaluates to true, a course-of-action (a set of statements) is followed otherwise another course-of-action is followed. This construct is also called decision construct as it helps in decision making.
14 Iterative ConstructsThe iterative or repetitive constructs means repetition of a set-of-statements depending upon a condition-test. A set-of-statements are repeated again and again till the condition or Boolean Expression evaluates to true. The iteration constructs are also called as looping constructs.
16 Selection Constructs VB provides two types of selection construct : 1) If statement2) Select Case statementThe If Statement : If statement of VB comes in various forms & are given below:1) If..Then Statement2) If..Then..Else Statement3) If..Then..ElseIf Statement4) Nested Ifs
17 If..Then StatementDef. : An If..Then statement tests a particular condition; if the condition evaluates to true, a course-of-action is followed otherwise it is ignored.Syntax :If (boolean expression) ThenstatementsEnd If
18 If..Then Statement Example 1. : If (Num>0) Then Print “It is a positive number”End ifExample 2 :If txtAge.Text>=18 ThenPrint “You are eligible to vote”
19 If..Then..Else StatementIf..Then..Else statement provides an alternate choice to the user i.e. if the condition is true then a set of statements are executed otherwise another set of statements are executed.Syntax :If (boolean Expression) ThenVB Statement(s)ElseEnd If
20 Examples of If..Then..Else If txtAge.Text>=18 ThenPrint “You are eligible to vote”ElsePrint “Sorry, You are not eligible to vote”End IfExample 2 :If Num Mod 2=0 ThenPrint “It is an Even Number”Print “It is an Odd Number”
21 If..Then..ElseIf Statement If..Then..ElseIf statement is used to test a number of mutually exclusive cases and only executes one set of statements for the case that is true first.Syntax :If (Boolean Expression) ThenStatement(s)ElseIf (Boolean Expression 2) ThenElseIf (Boolean Expression 3) Then:[ ElseEnd If
22 Example of If..Then..ElseIf If (Age<=4) ThenPrint “Your rate is free.”ElseIf (Age<=12) ThenPrint “You qualify for the children’s rate.”ElseIf (Age<65) ThenPrint “You must pay full rate”ElsePrint “You qualify for the seniors’ rate.”End If
23 Nested IfsA nested If is an if that has another If in its if’s body or in its else’s body. The nested if can have one of the following three forms :1. If (expresssion 1) ThenIf (expression 2 ) ThenStatement 1[ElseStatement 2End IfElsebody-of-else]
24 Nested Ifs 2. If (expression 1) Then body-of-if Else : Statement-1[ElseStatement-2]End If
25 Nested If’s 3) If (expression 1) Then : If (expression 2) Then Statement-1[ElseStatement-2]End IfElseIf (expression 3) ThenStatement-3Statement-4]
26 Example of Nested If’s If Num>0 Then Print “It is a positive number”ElseIf Num<0 ThenPrint “It is a negative number”Print “The number is equal to zero”End If
27 Select-Case Statement Select-Case is a multiple branching statement and is used to executed a set of statements depending upon the value of the expression. It is better to use Select-Case statement in comparison to If..Then..ElseIf Statement when the number of checks are more. There are 3 different forms of using Select-Case statements and are given below :
28 Different forms of Select-Case 1. Select Case : Simplest Form [Exact match]Select Case ExpressionCase Value’one or more visual basic statementsCase Else :End Select
29 Example of Form 1 Select Case byMonth Case 1,3,5,7,8,10,12 number_of_days=31Case 2number_of_days=28Case 4,6,9,11number_of_days=30End Select
30 Syntax of Form 2 Select Case : Second Form [Relational Test] Select Case ExpressionCase is relation :’one or more visual basic statements[Case Else :End Select
31 Example of Form 2 Select Case marks Case Is < 50 Result = “Fail” Result = “Grade B”Case Is < 75Result = “Grade A”Case ElseResult = “Grade A+”End Select
32 Third Form of Select Case Select Case : Third Format [Range Check]Select Case ExpressionCase exp1 To exp2:’one or more visual basic statements[Case Else:End Select
33 Example of Form 3 Select Case Age Case 2 to 4 : Print “PreNursery” Case 4 to 6 : Print “Kindergarden”Case 6 to 10 : Print “Primary”Case Else : Print “Others”End Select
34 Home Assignment 1Write a program in VB to compare three no’s and print the smallest number among these no’s.Write a program in VB to check the eligibilty of a person to vote. Display a message “You are eligible to vote” if the age of the person is greater than or equal to 18 otherwise print “Sorry! You are not eligible to vote”Write a program to compare two no’s and then print the square and cube of the larger number among these no’s.
35 Home AssignmentWrite a program to display the grade obtained by the child according to the marks obtained by him/her. Criteria for assigning the grades is given below : If marks are>=90 - Grade is A<90 and >80 – Grade is B<80 and >=70 – Grade is C<70 and >=60 – Grade is D<60 – Grade is E
36 Iterative Constructs (Looping Structures) Loop : A loop is said to be the set of instructions which are repeated again and again in a program.Types of Loops in VB :Sentinel-controlled Loop Structures : repeat statements until a special value called sentinel value (or the terminating value) is reached.Counter-controlled Loop Structures : repeat the set of statements until the value specified by the counter variable is reached.
37 Looping StructuresVB offers broadly following three types of looping structures :For..NextDo Loopa) Do While..Loopb) Do..Loop Whilec) Do Until..Loopd) Do..Loop UntilWhile..Wend
38 For..Next StatementThis type of statement is used when the user knows in advance how many times the loop is going to be executed.Syntax :For <counter Variable>=<start_val> To <end_val> Step <increment/Decrement Value>‘ One or more VB StatementsNext <counter Variable>
39 Examples Example 1 : Generate natural no’s from 1 to 100 For I = 1 To 100Print INext IExample 2 : Generate first 20 even no’s.For E = 2 to 40 Step 2Print ENext E
40 More ExamplesExample 3 : Generate odd no’s from 100 to 30 in a list box.For O = 99 to 31 Step -2ListO.AddItem(O)Next OExample 4 : Generate table of any number N.For T = 1 To NPrint N; “*”; T; “=”; N*TNext T
41 More Examples Example 5 : Find factorial of a given number N. : Fact=1 For I= 1 to NFact = Fact * INext IPrint “Factorial of ”; N; “=”; Fact
42 Home Assignment 2 Write Programs for the following problems : To Generate all the natural no’s from 200 to 500.To Generate the table of 10.To Generate all the even no’s from 200 to 400 in reverse order.To Print first 20 multiples of the number input by the user.
43 Do..Loop StructuresDo While..Loop : Do While loop is an entry controlled loop in which the condition is placed at the entry point. This statement executes the statements specified in the body of the loop till the condition evaluates to true. The loop may not be executed at all the if the condition is initially false.Syntax :Do While <condition or boolean expression>‘ One or more VB StatementsLoop
44 Examples of Do While..Loop Example 1 : Never executes loopDim A as ByteA=10Do While A>10A=A-1LoopExample 2 : Executes loopDim P as ByteP=20Do While P>5P=P-2
45 Do..Loop WhileDo Loop While is an exit controlled loop as the condition is placed at exit point. The body of the loop is going to be executed at least once whether the condition evaluates to true or false. Loop is executed as long as the result of the condition remains true.Syntax :DoOne or more VB StatementsLoop While <condition or Boolean Expression>
46 Examples Example 1 : Do num = InputBox (“Enter a number”) sum = sum + numLoop While num < > 0Here the statements inside the loop will be executed once no matter what the comparison test evaluates to.
47 Do..Until LoopDo Until loop is an entry controlled loop in which the condition is placed at the entry point. This statement executes the statements specified in the body of the loop till the condition evaluates to false. The loop may not be executed at all the if the condition is initially true.Syntax :Do Until <condition or boolean expression>‘ One or more VB StatementsLoop
48 Examples of Do Until..Loop Example 1 : Never executes loopDim A as ByteA=10Do Until A<10A=A-1LoopExample 2 : Executes loopDim P as ByteP=20Do Until P<5P=P-2
49 Do..Loop UntilDo Loop Until is an exit controlled loop as the condition is placed at exit point. The body of the loop is going to be executed at least once whether the condition evaluates to true or false. Loop is executed as long as the result of the condition remains false.Syntax :DoOne or more VB StatementsLoop Until <condition or Boolean Expression>
50 Examples Example 1 : Do num = InputBox (“Enter a number”) sum = sum + numLoop Until num = 0Here the statements inside the loop will be executed once no matter what the comparison test evaluates to.
51 While..WendWhile..Wend loop is functionally equivalent to the Do While..Loop. It executes a set of VB statements till the condition evaluates to true.Syntax :While <Condition>one or more vb statementsWend
52 Examples Example 1 : Generate the sum of first 10 natural no’s I = 1 While I<=10Sum = Sum + II = I + 1WendPrint “Sum of 10 natural no’s = ” ; Sum
53 Nested Loops A loop within another loop is called as Nested Loop. Example :For I = 1 to 5For J = 1 To 3Print JNext JPrintNext IInner LoopOuter Loop
54 Working of Nested Loops In nested loops the inner loop is executed completely for one time execution of the outer loop. In the Previous example the Inner Loop will be executed three times for every execution of the outer loop.Nested loops are very useful when there is a requirement to generate different kind of patterns as output.
55 Examples Sol : For I = 1 To 5 For J = 1 To I Print I; Next J Print Example : Program to generate the output given below :12 23 3 3Sol :For I = 1 To 5For J = 1 To IPrint I;Next JPrintNext I
56 Home Assignment 3 – Nested Loops Write programs to generate the following patterns :1 2)AA BA B CA B C D
57 Home Assignment 4 – Output Related Questions Specify the output of the following output related questions, assume that variables are declared :1) sum=0 2) sum = 0For I = 1 To 4 p=2 : q=4For J = 1 To 3 Do While p<=10sum = sum + J If p Mod 2 = 0 ThenNext J sum = sum + pPrint “Sum = ”;sum End IfNext I p=p+1LoopPrint sum
58 Output related questions 3) R=5 : S=3 4) M=2 : N=4Do Do Until M>12Print R, S N = N + MR = R If M Mod 3 = 0 ThenIf R = 7 Then N = N - MExit Do ElseEnd If N = N + MS = S + R End IfLoop While R <=10 M=M+1LoopPrint M, N
59 Home Assignment - 5Programming Questions : Develop programs for the followings :To generate the mirror image of the number entered by the user.To generate the prime numbers between 100 and 700.To Check whether the number entered by the user is a prime number or not.To print first 30 multiples of the number entered by the user.To generate the factorial of the number input by the user.
60 Home Assignment - 5To generate the Fibonacci series upto first 15 terms i.e …………..To find the sum of all the numbers divisible by 7 from 100 to 200.To check whether the year entered by the user is leap year or not.To find and print the sum of digits of the number entered by the user.To find and print the product of digits of the number accepted from the user.
61 Assessment ToolsStudents will be given Programming problems, output and error finding questions to test whether they understood the various concepts taught through this presentation.Various parameters are used to check the understanding of the concept and its implementation in Programming.All the parameters mention in the next slide have their own importance, so all these parameters needs to be checked by the Teacher teaching Programming.