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Class 14 functions in Python can return multiple values counting loops
while loops interactive loops sentinel loops
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functions in Python can return multiple values
(NOT true in many languages)
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functions in Python can return multiple values
def dater(): dateAsStr = input("Enter date: mm/dd/yyyy > ") dateAsList = dateAsStr.split("/") m=int(dateAsList[0]) d=int(dateAsList[1]) y=int(dateAsList[2]) return d, m, y
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functions in Python can return multiple values
def dater(): dateAsStr = input("Enter date: mm/dd/yyyy > ") dateAsList = dateAsStr.split("/") m=int(dateAsList[0]) d=int(dateAsList[1]) y=int(dateAsList[2]) return d, m, y >>> day, month, year = dater()
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functions in Python can return multiple values
>>> day, month, year = dater() Enter date: mm/dd/yyyy > 10/24/2018 >>> month 10 >>> day 24 >>> year 2018
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Scenario 1: input the number of employees
Problem: Compute the payroll for a company. input: hours and payrate for each worker output: total amount paid by company
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Scenario 1: input the number of employees
Problem: Compute the payroll for a company. input: hours and payrate for each worker output: total amount paid by company Know the number of times to go through the loop accumulate (total amount paid)
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Know the number of times to go through the loop
accumulate (total amount paid) input the total count of data, n initialize total loop n times input a value, x add x to total output total
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x=float(input("Enter a number>>")) total=total + x
Know the number of times to go through the loop accumulate (total amount paid) input the total count of data, n initialize total loop n times input a value, x add x to total output total for i in range(n): x=float(input("Enter a number>>")) total=total + x
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while loop
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while loop while <condition>: <body>
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We can imitate a for i in range loop with a while loop
for i in range(n): x=float(input("Enter a number>>")) total=total + x i=0 while i < n: x=float(input("Enter a number>> ")) total=total + x i=i+1
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Scenario 2: keep asking if there are more employees
Problem: Compute the payroll for a company. input: hours and payrate for each worker output: total amount paid by company DON'T KNOW the number of times to go through the loop accumulate (total amount paid)
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DON'T KNOW the number of times to go through the loop
accumulate (total amount paid) "Interactive Loop" initialize total set moredata to "yes" while moredata is "yes" input a value, x add x to total ask user if there is moredata output total
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DON'T KNOW the number of times to go through the loop
accumulate (total amount paid) "Interactive Loop" total = 0 moredata = "yes" while moredata== "yes": x=float(input("Enter a number>> ")) total = total + x moredata=input("Do you have more data? (yes or no)") print(total)
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Scenario 3: Too many employees. Use a sentinel
Problem: Compute the payroll for a company. input: hours and payrate for each worker output: total amount paid by company DON'T KNOW the number of times to go through the loop accumulate (total amount paid)
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General sentinel loop get the first data item while item is not the sentinel process the item get the next data item
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DON'T KNOW the number of times to go through the loop
accumulate (total amount paid) "Sentinel Loop" initialize total get first value, x while x is not the sentinel add x to total input a value, x output total
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DON'T KNOW the number of times to go through the loop
accumulate (total amount paid) "Sentinel Loop" total = 0 x = float(input("Enter a number, negative to quit>>")) while x>=0: total = total + x print(total)
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