When will strings become immutable?

Hi, I'm having trouble understanding this response.

What is the function of

[2]

in the code you provided?

The language on this is very confusing to me, because it seems to me the claim being made is that strings cannot be changed (because they are immutable) and yet in this very lesson we see several examples of the string being changed by appending new data to it. So, the string does change. Or, by your answer, it's not that the string is changing, but rather the data within the variable that contains the string is being changed. What's the difference? I'm completely lost on the semantics here.

treedweller — Strings can be treated as an array of individual characters, so s[2] would refer to the third character in a sting (of 3 or more characters). Since that line is attempting to modify the string by changing one of the characters, it fails because the string is immutable.

You forgot to show an example of where you saw a string being appended, but I suspect if you look again what's probably happening is that a variable that is pointing to a string is being reassigned to a new string that is being created by appending something new to an existing string. Reassigning the variable doesn't modify the string, it just associates a new one with the variable name.

You forgot to show an example of where you saw a string being appended, but I suspect if you look again what's probably happening is that a variable that is pointing to a string is being reassigned to a new string that is being created by appending something new to an existing string. Reassigning the variable doesn't modify the string, it just associates a new one with the variable name.

In the video, Craig performs the following:

dessert = "chocolate" + " and marshmallows" dessert = dessert + " and graham crackers"

Each line appending new text to the existing string. Is this not changing the string? I guess I'm just getting hung up on the semantics of saying it's the variable that points at a new string and not the string itself being changed. I've tried to think about it in a different way, in that the string itself is one whole object rather than a series of characters, so while it's possible to add things to the string, there are no reference points to change or remove a specific part of the string once it's been created. So I couldn't write something like "change every 5th word in this string to 'this word'" in code?

Would that be an accurate statement?

Although now I'm curious if it is possible to extract characters from a string. For instance, could I say something like:

sentence_string = "This is an entire sentence with several words."
vowel_string = (only the vowels from sentence_string)
vowel_count = (the number of vowels in sentence_string)

If that's possible, could I extract entire words? Maybe using the space as the delimiter in a filter function (if that's a thing)?

If you watch that part of the video where Craig shows the example:

dessert = dessert + " and graham crackers"

He also explains what it does:

And now, that might look like we changed the variable dessert. But what happened was that this statement, dessert + " and graham crackers", created a new string And we removed our already existing label and put it on the new string. We reassigned it. The old string, since it didn't have a label, it is essentially thrown away, like those leftovers in my office fridge. Remember, we didn't actually change the original string because we can't, right? And that's because strings are immutable.

So you can write code to "change every 5th word in this string to 'this word'", but it doesn't actually change the original strong. Instead, it creates a new string that has your desired contents.

Keep progressing in the lessons and later ones will show you ways to extract individual characters and whole words from strings.

Hey Steven, I really appreciate your replies! I guess what I've really been trying to figure out is why that distinction even matters, but I think I've come to understand it now based on your original comment.

s[2] = "x"

Because strings are immutable, we can't change just that one character in the string. But, since the variable can be reassigned to a new string, what we could do is extract s[0-1] and s[3*] (however that's accomplished), then concatenate a new string with the change we want to make.

So, the distinction is necessary because it emphasizes the restriction you have with manipulating strings using syntax that I'm assumimg can be used in other kinds of operations.

Do I have that right? Thanks again!

Sounds like you've got it. Keep progressing and future lessons will reinforce it.