# OperationsOnList.py
#
# Description: Either returns
#              - the sum of the numbers in a list
#              - the product of the numbers in a list
#
# Anne Lavergne
# Date: Feb. 26 2024


def performOpOnList(aList, anOperation = "+"):
  """Returns either the sum or the product of the numbers in a list
     depending on the value of the operator 'anOperation'.
     Returns 0 if 'anOperation' is not '+' or '*'."""

    # Figure out which operation to perform on the numbers in "aList"
  if anOperation == "+":
    # Initialize the accumulator variable to 0
    # We use "0" because we are adding numbers
    result = 0
    
    # For each number of the list
    for number in aList:
    
      # Add the number to the accumulator (running sum)
      result += number

  elif  anOperation == "*":
    # Initialize the accumulator variable to 1
    # We use "1" because we are multiplying numbers
    result = 1
    
    # For each number of the list
    for number in aList:
    
      # Add the number to the accumulator (running sum)
      result *= number
  else:
    result = "None"
    
  # Once done, return the result produced by this function:
  # the sum or product of all the numbers in the list
  # or 0 if 'anOperation' is not '+' or '*'
  return result
  
  
#*** Main part of my program

# Create a list
theList = [2,3,4]

# Test Case #1:
# Call performOpOnList with this list as an argument
theOp = "+"
theResult = performOpOnList(theList )
# And print its result i.e., the sum of the numbers in this list
print(F"The result of performing {theOp} of the list {theList} is {theResult}.")

# Test Case #2:
# Call performOpOnList with this list as an argument
theOp = "*"
theResult = performOpOnList(theList, theOp)
# And print its result i.e., the product of the numbers in this list
print(F"The result of performing {theOp} of the list {theList} is {theResult}.")

# Test Case #3:
# Call performOpOnList with this list as an argument
theOp = "$"
theResult = performOpOnList(theList, theOp)
# And print its result i.e., the product of the numbers in this list
print(F"The result of performing {theOp} of the list {theList} is {theResult}.")