How do I "backward" a string in matlab: turn "a" into "z", "b" into "y", "c" into "x", etc.
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I used the following code, but got an error...
function output_string = codeit(txt);
for ii = 1:length(txt)
input_char = txt(ii);
if input_char>='a'&&input_char<='z';
reverse_alphabet= ['z' 'y' 'x' 'w' 'v' 'u' 't' 's' 'r' 'q' 'p' 'o' 'n' 'm' 'l' 'k' 'j' 'i' 'h' 'g' 'f' 'e' 'd' 'c' 'b' 'a'];
reverse_alphabet_index = input_char - 'a' + 1;
output_char = reverse_alphabet(reverse_alphabet_index);
output_string(ii) = output_char;
elseif input_char>='A'&&input_char<='Z';
reverse_alphabet= ['Z' 'Y' 'X' 'W' 'V' 'U' 'T' 'S' 'R' 'Q' 'P' 'O' 'N' 'M' 'L' 'K' 'J' 'I' 'H' 'G' 'F' 'E' 'D' 'C' 'B' 'A'];
reverse_alphabet_index = input_char - 'A' + 1;
output_char = reverse_alphabet(reverse_alphabet_index);
output_string(ii) = output_char;
end
end
end
ans =
Feedback: Your function performed correctly for argument(s) 'azAZ'
Feedback: Your program made an error for argument(s) '`_^]\[ {|}~'
Your solution is _not_ correct.
3 个评论
Stephen23
2015-6-1
编辑:Stephen23
2015-6-1
@Darshan Kanungo: What is the specified/expected output for the input string '`_^]\[ {|}~' ? This is currently not specified in the question or the error message, so we have no idea how the function should behave with non-alphabetic characters. You need to specify this for us!
采纳的回答
Stephen23
2015-6-1
编辑:Stephen23
2015-6-1
>> char(219-'abc')
ans =
zyx
Note this assumes that the text consists only of lower-case alphabetic characters. If you want mixed case then this will be much more complicated.
EDIT in response to the OP completely rewriting their question, removing the original example and stating new requirements.
The new code given in the question is very complicated: solving this in a loop is slow and a waste of MATLAB's code vectorization abilities. Here is a completely vectorized function based on isstrprop that reverses only the alphabetic characters (keeping case the same) and ignores all other characters:
function str = str_rev(str)
idx = isstrprop(str,'upper');
str(idx) = char(155-str(idx));
idx = isstrprop(str,'lower');
str(idx) = char(219-str(idx));
end
And some examples showing it in action:
>> str_rev('abc')
ans =
zyx
>> str_rev('AbcD')
ans =
ZyxW
>> str_rev('Hello World!')
ans =
Svool Dliow!
更多回答(2 个)
Jan
2015-6-1
function out = codeit(in)
lut = char(1:255);
lut(['a':'z', 'A':'Z']) = ['z':-1:'a', 'Z':-1:'A'];
out = lut(in);
0 个评论
charu sharma
2015-8-26
For a simple understanding you can follow this too: http://farzicoders.blogspot.in/2015/08/write-function-called-codeit-that-takes.html
1 个评论
Guillaume
2015-8-26
I wouldn't classify this answer as spam, the link is relevant to the question (as long as it does not disappear).
However, the answer posted in the link is a poor example of coding (unnecessary loops, unnecessary conversions, unnecessary use of temporary variables), so is of little value.
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