9.2. Reversing Text

Run this next one, and look at how a simple change to the pattern gives a very different result. Here we’ll combine before rather than afterward, changing only Step 4 (how values are accumulated).

# STEP 1: INITIALIZE ACCUMULATORS newStringA = "" newStringB = "" # STEP 2: GET DATA phrase = "Happy Birthday!" # STEP 3: LOOP THROUGH THE DATA for letter in phrase: # STEP 4: ACCUMULATE newStringA = letter + newStringA newStringB = newStringB + letter # STEP 5: PROCESS RESULT print("Here's the result of using letter + newStringA:") print(newStringA) print("Here's the result of using newStringB + letter:") print(newStringB)

Why do you think newStringB has all the letters, but in the reverse order?

• Because we add each new letter at the end of newStringB.
• Each new letter gets added at the end, which creates a reversal.
• Because newStringA is adding the characters from left to right.
• How would that reverse the other string?
• Because we called a reverse function.
• There is no reverse function in this program.
• Because the for loop is doing a reversal
• The same for loop is creating both an in-order copy of the string and a reversed order of the string. The for loop is the same in both cases.

Write the code to make a palindrome with the string “popsicle”. Palindromes read the same foward and backwards. Example: appleelppa

# INITIALIZE ACCUMULATORS newStringA = "" newStringB = "" # NAME DATA word = "popsicle" # LOOP THROUGH THE DATA for letter in word: # ACCUMULATE RESULT newStringA = letter + newStringA newStringB = newStringB + letter # DISPLAY RESULT print("Here's the result of using newStringB + letter:") print(newStringB + newStringA)

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