Check if a string contains only certain characters

[Guerra]

Hello, world

Im trying to create a mechanism to check if an input string contains only the few allowed characters, something like

for i in string:

    if i != "a" or "b" or "c"
        print "invalid character"

you know?

I found out that you can split a string into itens in a list (https://groups.google.com/d/msg/mitappinventortest/GbK4eXiaHe0/1gBzQqigAAAJ)


So I tried this version in which I tried to adapt this code to take an input from a textbox and print an output in a second textbox:

All I got was the output invalid character no matter what the input was. Does anyone know why?

Thanks!

[Pavitra]

Please take a look at this: https://community.thunkable.com/t/adding-up-specific-words-in-text-string/2423/18?u=pavi2410

[Guerra]

This doesn't really answer my question, but it does give me an idea to go around the problem. I'll try another approach. Thanks!

[Guerra]

SOLVED
It's probably more junky and uses more memory (I had to create four global variables bc I'm using them in another part of my code) than if I had written directly in Javascript or something else. But, hey, it works!
Basically, to check if a given string contains ONLY the allowed characters you can add 1 to a counter for every valid character in the string. If the length of the string equals the counter, there are no invalid characters in that string.

[Abraham Getzler]

Also see http://appinventor.mit.edu/explore/ai2/support/blocks/text.html#contains

for each character c in the string

  if contains("ABCD",c) then

    correct = correct + 1

  end if

end for

ABG