Unit2 control statements
- 1. Unit 2 Basic Python : Control Statements
- 2. control structures • 3 control structures • Sequential structure • Built into Python • Selection structure • The if statement • The if/else statement • The if/elif/else statement • Repetition structure • The while repetition structure • The for repetition structure
- 3. 3 Sequence Control Structure Fig. 3.1 Sequence structure flowchart with pseudo code. add grade to total add 1 to counter total = total + grade; counter = counter + 1;
- 4. 4 if Selection Structure Fig. 3.3 if single-selection structure flowchart. print “Passed”Grade >= 60 true false
- 5. 5 if/else Structure Fig. 3.4 if/else double-selection structure flowchart. Grade >= 60 print “Passed”print “Failed” false true
- 6. 6 if/elif/else Selection Structure condition a true false . . . false false condition z default action(s) true true condition b case a action(s) case b action(s) case z action(s) if statement first elif statement last elif statemen t else stateme nt Fig. 3.5 if/elif/else multiple-selection structure.
- 7. 7 while Repetition Structure • Repetition Structures • Allow a program to repeat an action while a condition is true • Using while Repetition • Action(s) contained within the body of the loop • Condition should evaluate to false at some point • Otherwise infinite loop and program hangs
- 8. 8 while Repetition Structure true false Product = 2 * product Product <= 1000 Fig. 3.8 while repetition structure flowchart.