1. © Janice Regan, CMPT 128, Jan 2007 0 CMPT 128: Introduction to Computing Science for Engineering Students Control Structures Nested ifs, switch statements

2. © Janice Regan, CMPT 128, Jan 2007 1 Multiple Selections (Nested if) if (condition) { // Series of actions to be taken when the condition is true action 1A; action nA; } else { if (condition 2) { // Series of actions to be taken when condition is false and condition2 true action 1B; action nB; } else { // Series of actions to be taken when condition and condition 2 are false action 1C; action nC; }

3. © Janice Regan, CMPT 128, Jan 2007 2 Flowchart for multiple selection condition2 Statement 1A; Statement nA; T F Statement 1C; Statement nC; condition F Statement 1B; Statement nB; T

4. © Janice Regan, CMPT 128, Jan 2007 3 Multiple Selections (elseif) if (condition) { // Series of actions to be taken when condition is true action 1A; action nA; } else if (condition 2) { // Series of actions to be taken when condition is false and condition 2 is true action 1B; action nB; } else { // Series of actions to be taken when the condition and condition2 are false action 1C; action nC; }

5. © Janice Regan, CMPT 128, Jan 2007 4 Multiple Selections (Nested if) if (condition) { if (condition 2) { // Series of actions to be taken when condition is true and condition2 true action 1A; action nA; } else { // Series of actions to be taken when condition is true and condition 2 is false action 1B; action nB; } else { // Series of actions to be taken when condition is false, condition2 either action 1C; action nC; }

6. © Janice Regan, CMPT 128, Jan 2007 5 Flowchart for multiple selection condition2 Statement 1; Statement n; T F Statement 1C; Statement nC; condition F Statement 1A; Statement nA; T F

7. © Janice Regan, CMPT 128, Jan 2007 6 Flowchart for multiple selection condition Statement 1A; Statement nA; T F Statement 1C; Statement nC; condition&& condition2 F Statement 1B; Statement nB; T

8. © Janice Regan, CMPT 128, Jan 2007 7 Multiple Selections (elseif) if (condition && condition2) { // Series of actions to be taken when condition is true and condition2 true action 1A; action nA; } else if (condition) { // Series of actions to be taken when condition is true and condition2 is false action 1; action n; } else { // Series of actions to be taken when the condition and condition2 are false action 1; action n; }

9. © Janice Regan, CMPT 128, Jan 2007 8 The switch statement  An alternative method to if statements with multiple else clauses  The controlling expression (selector) must have an integral type  Characters also work because they can be converted to integers  Case labels are particular values of the controlling expression  Break statements exit from the switch structure

10. © Janice Regan, CMPT 128, Jan 2007 9 switch Structures switch(controling expression) { case value1: statements1; break; case value2: statements2; break;... case valuen: statementsn; break; default: statements; }

11. © Janice Regan, CMPT 128, Jan 2007 10 switch Statement expression = value1 expression = value2 expression = valuen

12. © Janice Regan, CMPT 128, Jan 2007 11 Sample case statement /* This is in a loop that reads */ /* nextInt each time */ switch (nextInt) { case 0: count0++; break; case 1: count1++; break; case 2: count2++; break; case 4: count4++; break; case 5: count5++; break; case 6: count6++; break; case 7: count7++; break; default: countOther++; }