If-Else Statement

1. If-Else Statement

2. Review • So far… • Input • Output • Remember and • Modify data • Yet to come… • Decision branching • Looping

3. The if-else Statement if (expression)    statement1else    statement2 allows a program to take one of two branches or paths of execution depending on the value of some expression

4. The if-else Statement if (expression)    statement1else    statement2 allows a program to take one of two branches or paths of execution depending on the value of some expression

5. The if-else Statement if (expression)    statement1else    statement2 allows a program to take one of two branches or paths of execution depending on the value of some expression

6. The if-else Statement if (expression)    statement1else    statement2 allows a program to take one of two branches or paths of execution depending on the value of some expression

7. Warning! if (temperature > 100); {cout << “It’s hot outside”; }

8. Example #1 if (4) cout << “hello”;

9. Example #2 if (0) cout << “hello”;

10. Example #3 cout << “enter radius: “; cin >> radius; if (radius <= 0) { cout << “Error: no circle has non-positive radius!” << endl; exit(1); }area = PI * radius * radius; cout << “The circle with radius ” << radius << “ has area ” << area << “.” << endl;cout << “Ending this example...” << endl;

11. Example #3 (revisited) cout << “enter radius: “; cin >> radius; if (radius <= 0) cout << “Error: no circle has non-positive radius!” << endl;else{    area = PI * radius * radius; cout << “The circle with radius ” << radius << “ has area ” << area << “.” << endl;} cout << “Ending this example...” << endl;

12. Tabs vs Spaces if (tabs == true) {cout << “This is”; cout << “ an example”; cout << “ of bad”; cout << “indentation.”;cout << endl;}

13. const int MAX_A = 100;const int MIN_A = 90;const int MIN_B = 80; cout << “enter average: ”;cin >> ave;if (ave > MAX_A)cout << “Error: average out of range!” << endl;else    if (ave >= MIN_A)        grade = ‘A’;    else        if (ave >= MIN_B)            grade = ‘B’;        else            if (ave >= MIN_C)                grade = ‘C’;            else                grade = ‘F’;

14. const int MAX_A = 100;const int MIN_A = 90;const int MIN_B = 80; cout << “enter average: ”;cin >> ave;if (ave > MAX_A)cout << “Error: average out of range!” << endl;else    if (ave >= MIN_A)        grade = ‘A’;    else        if (ave >= MIN_B)            grade = ‘B’;        else            if (ave >= MIN_C)                grade = ‘C’;            else                grade = ‘F’;

15. const int MAX_A = 100;const int MIN_A = 90;const int MIN_B = 80; cout << “enter average: ”;cin >> ave;if (ave > MAX_A)cout << “Error: average out of range!” << endl;else    if (ave >= MIN_A)        grade = ‘A’;    else        if (ave >= MIN_B)            grade = ‘B’;        else            if (ave >= MIN_C)                grade = ‘C’;            else                grade = ‘F’;

16. const int MAX_A = 100;const int MIN_A = 90;const int MIN_B = 80; cout << “enter average: ”;cin >> ave;if (ave > MAX_A)cout << “Error: average out of range!” << endl;else    if (ave >= MIN_A)        grade = ‘A’;    else        if (ave >= MIN_B)            grade = ‘B’;        else            if (ave >= MIN_C)                grade = ‘C’;            else                grade = ‘F’;

17. const int MAX_A = 100;const int MIN_A = 90;const int MIN_B = 80; cout << “enter average: ”;cin >> ave;if (ave > MAX_A)cout << “Error: average out of range!” << endl;else    if (ave >= MIN_A)        grade = ‘A’;    else        if (ave >= MIN_B)            grade = ‘B’;        else            if (ave >= MIN_C)                grade = ‘C’;            else                grade = ‘F’;

18. cin >> ave;if (ave > MAX_A)cout << “Error: average out of range!” << endl;else if (ave >= MIN_A)    grade = ‘A’;else if (ave >= MIN_B)    grade = ‘B’;else if (ave >= MIN_C)    grade = ‘C’;else if (ave >= MIN_D)    grade = ‘D’;else if (ave >= 0)    grade = ‘F’;else    exit(3);

19. The exit Function return 0; exit (3);

20. End of Session