TypeError: string indices must be integers - Python3

Question

Problem

So, my problem is that I'm getting a TypeError: string indices must be integers , on this line: userCHR += str(user[i]) , but the code looks fine to me. Can someone help me?

Python Code

user = input("Please enter a string: ")
user = user.upper()

userCHR = ""

for i in user:
    userCHR += str(user[i])

print(userCHR)

Answer 1

If I'm not wrong, the i is already a string. Maybe you can try:

for i in user:
  userCHR += i

Answer 2

A for loop returns the character in the string, not the integer location, in Python.

From

userCHR += str(user[i])

To

userCHR += i

New Code

user = input("Please enter a string: ")
user = user.upper()

userCHR = ""

for i in user:
    userCHR += i

print(userCHR)