Exercise 07-06:
Write a program that reads three strings. The first string is your source string. The second one has the characters that will be replaced by the ones in the third string. Your program should create a fourth string, the resulting string, which is the first string with the characters of the second replaced by the ones in the third.
1st string: AATTCGAA
2nd string: TG
3rd string: AC
Result: AAAACCAA
Answer:
##############################################################################
# Python From Scratch
# Author: Nilo Ney Coutinho Menezes
# Editora Novatec (c) 2010-2025 - LogiKraft 2025
# Site: https://pythonfromscratch.com
# ISBN: 978-85-7522-949-1 (Paperback), 978-85-7522-950-7 (hardcover), 978-85-7522-951-4 (ebook)
#
# File: chapter 07/exercise-07-06.py.py
##############################################################################
first = input("Enter the first string: ")
second = input("Enter the second string: ")
third = input("Enter the third string: ")
if len(second) == len(third):
result = ""
for letter in first:
position = second.find(letter)
if position != -1:
result += third[position]
else:
result += letter
if result == "":
print("All characters were removed.")
else:
print(
f"The characters {second} were replaced by "
f"{third} in {first}, resulting in: {result}"
)
else:
print("ERROR: The second and third strings must have the same length.")