When execute the below code ? the error message appear 'Index exceeds the number of array elements'?

1 view (last 30 days)
M_h="FFFFFFFFFFFFFFFF";
M="";
for i=1:16
M(end+1:end+4)=dec2bin(hex2dec(M_h(i)), 4);
end
Warning: Hexadecimal numbers representing integers greater than or equal to flintmax might not be represented exactly as double-precision floating-point values.
Index exceeds the number of array elements. Index must not exceed 1.

Accepted Answer

Jérôme
Jérôme on 12 Sep 2022
M_h and M are string arrays because you used "". Here, you want to work with char arrays using '' (See for example these links for details about them: https://www.mathworks.com/help/matlab/characters-and-strings.html, https://www.mathworks.com/help/matlab/ref/char.html, https://www.mathworks.com/help/matlab/ref/string.html).
If you use the following code, you will not have the error anymore:
M_h='FFFFFFFFFFFFFFFF';
M='';
for i=1:16
M(end+1:end+4)=dec2bin(hex2dec(M_h(i)), 4);
end
  3 Comments
Jérôme
Jérôme on 19 Sep 2022
In Text in String and Character Arrays, you can see that MATLAB shows how to access individual characters of a char array, but not for a string. Because strings are made to work at a higher level, not to work characters per characters, which is the perfect job for char arrays.
In your case, you can simply convert the string to a char array before your operation, and convert it back to a string after that:
M_h="FFFFFFFFFFFFFFFF";
M_h2 = convertStringsToChars(M_h);
M2='';
for i=1:16
M2(end+1:end+4)=dec2bin(hex2dec(M_h2(i)), 4);
end
M = convertCharsToStrings(M2);
Otherwise, if you really want to manipulate string directly, I imagine it's possible using the function extractBetween.

Sign in to comment.

More Answers (1)

Walter Roberson
Walter Roberson on 21 Sep 2022
Using extractBetween() as suggested by @Jérôme is the approved way to work with characters inside strings. But you can also go to a lower level... which will give you faster code.
Double-quotes like you had is used for a string array, so below I show looping over a string array and using {} to extract characters
M_h = ["FFFFFFFFFFFFFFFF"; "DEADBEAFDEADBEAF"];
M = strings(size(M_h));
for K = 1 : numel(M_h)
this_M_in = M_h{K};
this_M_out = blanks(64);
for i=1:16
this_M_out(i*4-3:i*4)=dec2bin(hex2dec(this_M_in(i)), 4);
end
M(K) = string(this_M_out);
end
M
M = 2×1 string array
"1111111111111111111111111111111111111111111111111111111111111111" "1101111010101101101111101010111111011110101011011011111010101111"

Categories

Find more on Characters and Strings in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!