Running Totals

1. Running Totals CSIS 1595: Fundamentals of Programming and Problem Solving 1

2. Running Totals • Goal: Creating a cumulative value based on data entered/computed by program • Generally done with a loop • Algorithm: • “Accumulator” variable kept • Initialize accumulator to value before any data • Each time through loop, update accumulator based on current data in terms of: • Current data • Previous value of accumulator

3. Trip Mileage Example • Goal: Keep track of total mileage driven on trip • Algorithm: • Prompt user for mileage this stage • Increment total mileage by amount entered by user each stage • Initially: total mileage = 0 • Use sentinel loop to decide when to quit

4. Trip Mileage Example

5. Running Products • Can increment running totals in ways other than addition • Example: • Place a penny on first square of chess board • Double number of pennies on each subsequent square • How many pennies on each square? • Design: • Initial value of pennies = 1 (number on first square) • Doublepennies each time through loop by multiplying by 2 • pennies *= 2 • Since we know how many squares there are, we can use a for loopfrom 1 to 65

6. Running Products

7. Running Maximums/Minimums • May want to find largest/smallest/etc. in some list of values • Example: • User enters names and corresponding grades • Program then prints name of student with highest grade

8. Running Maximums/Minimums • Key idea: Each time through loop, keep track of: • Highest grade so far • Name of student with the highest grade so far • Modifying accumulators in loop: • Prompt for name, grade of next student • Compare their grade with highest grade so far • If the new grade is higher: • The highest grade so far is the new grade • The student with the highest grade is the new name • Initialization: • Prompt for name, grade of firststudent • Initialize highest name, grade to those values

9. Running Maximums/Minimums