FP 201 Unit 3

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FP 201 Unit 3

  1. 1. Unit 3Understand selection control structures
  2. 2.  At the end of this presentation, students will be able to: • Understand selection control structures • Describe the structure and working of simple if statements • Describe the structure and working of nested if statements • Describe the structure and working of switch statements
  3. 3.  Statements executed one by one. Simplest Example : int x = 5; [S1] int power = x*x; [S2] cout << “n” << power; [S3] Entry S1 S2 S3 Exit
  4. 4.  C++ supports two types of program control: • selection control structures • looping control structures
  5. 5.  Purpose: • to evaluate expressions/condition • to direct the execution of the program (depending on the result of the evaluation). The most commonly used selection statements are: • if statement • if-else statement • nested-if statement • switch statement
  6. 6.  Used to execute a set of statements when the given condition is satisfied. Syntax if (<condition>) { <Conditional statements>; } Conditional statements within the block are executed when the condition in the if statement is satisfied.
  7. 7. false conditionConditional statement true Next statement
  8. 8.  Example: if (age > 21) cout << “n Anda layak mengundi”;
  9. 9. false age > 21Anda layak mengundi true Next statement
  10. 10.  Program InputValue.cpp illustrates the execution of a simple if statement. The program checks whether the given number is greater than 100.
  11. 11. startDeclare: number variable Read number false number<100 truePrint result “Number is less than 100” end
  12. 12. #include <iostream>using namespace std;int main(){ int num; cout << "Enter integer number: "; cin >> num; if(num<100) cout<<"Number is less than 100"<<endl; return 0;}
  13. 13.  Executes the set of statements in if block, when the given condition is satisfied. Executes the statements in the else block, when the condition is not satisfied.Syntax if (<condition>) { <Conditional statements1>; } else { <Conditional statements2>; }
  14. 14. true false condition Conditional statement in elseConditional statement in if body body Next statement
  15. 15.  Example: if (E4162 == ‘L’) cout << “n Anda lulus”; else cout << “n Anda gagal”;
  16. 16. true false E4162 == ‘L’Anda lulus Anda gagal Next statement
  17. 17.  Program Checks.cpp illustrates the use of the if-else statement. This program accepts a number, checks whether it is less than 0 and displays an appropriate message.
  18. 18. start Declare: number variable Read number true false number<0 Print Print“Negative” “Positive” end
  19. 19. #include <iostream>using namespace std;int main(){ int num; cout << "Enter integer number: "; cin >> num; if(num<0) cout<<"Negative"<<endl; else cout<<"Positive"<<endl; return 0;}
  20. 20. 1. Accept a number from the keyboard and check whether it is dividable by 5 (if else). Hint: Use the modulus operator, %, to check the divisibility.
  21. 21. #include <iostream>using namespace std;int main(){ int no; cout<<"Enter integer number: "; cin>>no; if(no%5==0) cout<<"dividable by 5"<<endl; else cout<<"undividable by 5"<<endl; return 0;}
  22. 22. 2. Accept two integer numbers from the keyboard and find the highest among them.
  23. 23. #include<iostream>using namespace std;int main(){ int no1,no2; cout<<"Enter two integer number: "; cin>>no1>>no2; if(no1>no2) cout<<"Number 1 is highest than number 2"<<endl; else cout<<"Number 2 is highest than number 1"<<endl; return 0;}
  24. 24.  The if statements written within the body of another if statement to test multiple conditions is called nested if. Syntax if (<Condition 1>) { if (<Condition 2>) { <Conditional statements1>; } else { <Conditional statements2>; Inner if } } condition Outer if else { condition <Conditional statements3>; }
  25. 25. false Condition 1 true false Condition 2 true Conditional ConditionalConditional statements1 statements2 statements3 Next statement
  26. 26.  The program Highest.cpp illustrates the use of nested if statements. The program accepts three integers from the user and finds the highest among the three.
  27. 27. #include <iostream>using namespace std; if(x>y) {int main() if(x>z){ cout<<x<<" is the highest"; int x,y,z; else cout<<z<<" is the highest"; cout<<"Enter x: "; } cin>>x; else cout<<"Enter y: "; { cin>>y; if (y>z) cout<<"Enter z: "; cout<<y<<" is the highest"; cin>>z; else cout<<z<<" is the highest"; } return 0; }
  28. 28. #include <iostream>using namespace std;int main(){ int x,y,z; cout<<"Enter x: "; cin>>x; cout<<"Enter y: "; cin>>y; cout<<"Enter z: "; cin>>z; if(x>y&&x>z) cout<<x<<" is the highest"; else if (y>x&&y>z) cout<<y<<" is the highest"; else cout<<z<<" is the highest"; return 0;}
  29. 29. #include <iostream>using namespace std;int main(){ int a,b,c; cout<<"Enter a: "; cin>>a; cout<<"Enter b: "; cin>>b; cout<<"Enter c: "; cin>>c; if(a>c&&b>c){ if(a>b) cout<<a<<" is the highest"; else cout<<b<<" is the highest"; } else{ if(c>a&&c>b) cout<<c<<" is the highest"; else cout<<b<<" is the highest"; } return 0;}
  30. 30. #include<iostream>using namespace std;void main(){ int x=2; if(x<=3) if(x!=0) cout << "Hello"; else cout<< "hello"; if(x>3) if(x!=0) cout << "Hi"; else cout << "hi";}
  31. 31.  Note that the first line does not end with a semicolon. The curly brackets are necessary only if there are several statements.
  32. 32.  Switch statement is C++s multi-way branch Allows to specify a number of different cases, rather than simply true or false Switch statement requires an expression after the word switch and then it jumps to the statement whose case matches the expression A break statement passes the control outside switch structure.
  33. 33. Syntax switch (expression) { case expression_1 : statement sequence; break; case expression_2 : statement sequence; break; ………….. case expression_n : statement sequence; break; default : statement sequence; }
  34. 34. statementexpression_1 break sequence statementexpression_2 break sequence default break
  35. 35.  Example: int main() { char pilih; cout << “n Menu Utaman”; cout << “ M = Masukkan duit n”; cout << “ K = Keluarkan duitn”; cout << “ E = Exitn”; cout << “ Pilihan anda: “; cin >> pilih; switch (pilih) { case ‘M’ : cout << “Sila tambah duit anda”;break; case ‘K’ : cout << “Hanya boleh keluar duit”;break; case ‘E’ : cout << “Keluar dari Menu Utama”;break; default : cout << “Pilihan yang salah”; } }
  36. 36.  Program SwitchDemo.cpp illustrates switch case execution. In the program, the switch takes an integer value as input and displays the month based on the integer entered.
  37. 37. #include <iostream>using namespace std;int main(){ int month; cout<<"Enter number: "; cin>>month; switch (month) { case 1: cout<<"January"; break; case 2: cout<<"February"; break; case 3: cout<<"March"; break; case 4: cout<<"April"; break; default: cout<<"wrong choice"; } return 0;}
  38. 38. 1. Write a program to accept number of a day for the week and print the day 1 – Sunday 5 – Thursday 2 – Monday 6 – Friday 3 – Tuesday 7 – Saturday 4 - Wednesday
  39. 39. #include <iostream> case 5: cout<<"Thursday";using namespace std; break;int main() case 6: cout<<"Friday";{ int day; break; case 7: cout<<"Saturday"; cout<<"Enter number: "; break; cin>>day; default: cout<<"wrong switch (day) choice"; { } case 1: cout<<"Sunday"; break; return 0; case 2: cout<<"Monday"; } break; case 3: cout<<"Tuesday"; break; case 4: cout<<"Wednesday"; break;
  40. 40.  Write a program that able to check either a character is a vowel or not by using switch statements and if else statement
  41. 41. #include <iostream>using namespace std;int main(){ case o: char ch; case O: cout<<"Vowel"; break; cout<<"Enter character: "; cin>>ch; case u: case U: cout<<"Vowel"; switch (ch) break; { default: cout<<"Not vowel"; case a: } case A: cout<<"Vowel"; return 0; break; } case e: case E: cout<<"Vowel"; break; case i: case I: cout<<"Vowel"; break;
  42. 42. #include<iostream>using namespace std;void main(){ char ch; cout<<"Enter character: "; cin>>ch; if(ch==a||ch==A||ch==e||ch==E||ch==i ||ch==I||ch==o||ch==O||ch==u||ch==U) cout<< ch << " is a voweln"; else cout<< ch << " is not a voweln";}
  43. 43. In this presentation, you learnt the following: Program controls are used to change the sequential flow of a program. The two types of program controls are selection control structures and looping control structures In C++, the selection control structures include if and switch statements.

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