Control Structures Lecture Notes PDF

Control Structures You can create any program or algorithm by using a combination of the three constructs below: 1) Sequence structures– execute statements in sequential order – start at the beginning and continue in sequential order 2) Selection structures– selectively execute statements - Also...

Control Structures You can create any program or algorithm by using a combination of the three constructs below: 1) Sequence structures– execute statements in sequential order – start at the beginning and continue in sequential order 2) Selection structures– selectively execute statements - Also called a branch or decision -requires a condition to determine when to execute statements 3)Repetition structures– repeat statements more than once -Also called a loop -needs a stop condition, i.e, the program will continue to loop until some condition is met Three Basic Structures Each structure has one entry and one exit point Structures attach to others only at entry or exit points Flowchart for sequential structures Example Flowcharts for typical decision (selection) Lab example: End Start Add Output Input a numbers result number 𝑥 Yes Input a No Yes 𝑦 Subtract Is 𝑥 number even? from 𝑥 𝑦 Example Flowcharts for typical repetition (loop) structures Back-pointing arrows show statements that will be repeated Remember this lab example? Add number Start to total No Input a Is number Let total be 0 >10? number Yes Output total End