# Array of ASCII Characters to String

20 views (last 30 days)
Parker on 30 Nov 2023
Commented: Steven Lord on 30 Nov 2023
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.

Stephen23 on 30 Nov 2023
Edited: Stephen23 on 30 Nov 2023
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 on 30 Nov 2023
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'

Benjamin Kraus on 30 Nov 2023
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]")), "");

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