Summary Programming Logic and Design Ch 5

Chapter 5
Create loop logic
 Advantages of looping
 Makes programming efficient
 Write one set of instructions to operate multiple, separate sets of data
 Less time required for designing and coding, less errors, shorter compile time
 Loop: structure that repeats actions while some condition remains true

Use a loop control variable
 Loop control variable: variable that determines whether loop execution will continue
 As long as a condition remains true, the statement in a while loop's body will continue
executing
 Control number of repetitions (3 important steps for functionality)
 Loop control variable initialized before entering loop
 Loop control variable tested
 Variable is altered in body of loop so the tested condition that starts the loop will
eventually be false
 Repetitions controlled by:
 Counter - used to create a definite counter-controlled loop
 Sentinel value - used to create indefinite loop (user determines loop execution)

 Definite loop: executes a predetermined number of times
 Indefinite loop: performed different number of times each time, user decides how many
times
 Counter-controlled loop: Program counts repetitions
 Loop control variables altered by
 Incrementing ==> count = count + 1
 Decrementing ==> count = count - 1
 Can also add or subtract bigger values, like for every second number or year
 Counter: any numeric variable that counts the number of times an event has occurred,
usually starts with 0
 Why start counter with 0: arrays start counting at 0, application numbering start with 0,
contains number of times loop has executed which might be useful


Create nested loops
 Needed when values of two or more variables repeat to produce every combination of values
 Nested loops: loops within loops
 Outer loop: loop that contains the other loop
 Inner loop: the loop that is contained
 Each loop has its own control variable