Array of ASCII Characters to String

word = string(input("Input: ","s"));
word2 = [];
for n = char(97:122)
    for x = 1:strlength(word)
        if contains(word{1}(x:x),n)
            word2(x) = n;
        end
    end
end
word = string(word2);

I want to have any input and only use the letters in it. I went through this process but it returns a character array of ASCII values, either how do I remove all no letters from a string input or how do I convert an ASCII array back to a string.

Answer 1

[Stephen23]

Forget about loops and doing everything one-at-a-time as if MATLAB was some poor low-level language.

Think in terms of arrays and indexing. Here is one approach:

S = "UPPERCASElowercase!£%&*"

S = "UPPERCASElowercase!£%&*"

X = S{1}<97 | S{1}>122;
S{1}(X) = []

S = "lowercase"

You could also use ISSTRPROP, or REGEXPREP, or various other approaches that do not require any loops.

[Steven Lord]

I'm partial to isstrprop, as you mentioned in your last sentence, as it doesn't depend on "magic numbers".

S = "UPPERCASElowercase!£%&*"

S = "UPPERCASElowercase!£%&*"

lowercaseLetterLocations = isstrprop(S, "lower");
S{1}(lowercaseLetterLocations)

ans = 'lowercase'

Answer 2

[Benjamin Kraus]

The issue with your current code is that on line 2 you need to initialize word2 as a character vector instead of a double vector.

Because you are initializing word2 as a double vector, when you attempt to assign a new value into the double vector, it is being cast into a double (even if you try to use a character instead).

word = string(input("Input: ","s"));
word2 = ''; % This needs to be a character vector (''), not a double vector ([]).
for n = char(97:122)
    for x = 1:strlength(word)
        if contains(word{1}(x:x),n)
            word2(x) = n;
        end
    end
end
word = string(word2);

However, there are far easier ways to do what you are trying to do.

For example:

Option 1

word = input("Input: ","s"); % No cast to string
word2 = deblank(string(regexprep(word, '[^a-z]', ' '))); % Replace ' ' with '' to remove the letters.

Option 2

word = input("Input: ","s"); % No cast to string
word2 = word;
word2(word2<97|word2>122) = ' '; % Replace with [] to remove the letters.
word2 = deblank(word2);

Option 3

word = string(input("Input: ","s"));
word2 = deblank(replace(word, regexpPattern("[^a-z]")," "));

Option 4

word = string(input("Input: ","s"));
word2 = strjoin(extract(word, regexpPattern("[a-z]")), "");