How do I do char2num (assume Ascii)?

num2 char is easy enough num = char(122) returns 'z' ; but how can I get back to the ascii value from a char?

Do I really have to do all this:

val = unicode2native(ch(1:1),'US-ASCII');

I suppose I can make

function val = char2num(ch)  % return a single ascii value
if ischar(ch) || isstring(ch)
    val = unicode2native(ch(1:1),'US-ASCII');
    val = val(1:1); % because if it's a string ch(1:1) is the first string not the char
else % it's already a number?
    ch = mod(ch,256); % Too big? take LSB
    % oddly ML mod() allows fractions so ...
    val = uint8(ch); % round if needed
end

But surely there is a built in function that I just can't find

Answer 1

[Stephen23]

https://www.mathworks.com/help/matlab/matlab_prog/unicode-and-ascii-values.html

txt = char(120:122)

txt = 'xyz'

num = double(txt)

num = 1×3

120 121 122

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

If you have a container array (e.g. cell array or string array) then of course you will need to use a loop or CELLFUN/ARRAYFUN or something of that nature. For a scalar string array you could simply access its content using curly braces:

str = "xyz";
vec = double(str{1})

vec = 1×3

120 121 122

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

[Gavin]

Doh

Then I just need

num = uint8(double(txt)

to get a byte, and it takes either string or char vector

Correction:

since

str = "xyz";

vec = double(str{1})

vec = 1×3

120 121 122

and it DIDN'T just take that first char I then need

num = uint8(vec(1))

to get that first char

[Stephen23]

txt = char(120:122)

txt = 'xyz'

num = uint8(txt)

num = 1×3

120 121 122

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

You can add CHAR if you want it to work with both character arrays and scalar strings:

num = uint8(char(txt))

num = 1×3

120 121 122

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

[Stephen23]

str = "xyz";
num = uint8(str{1}(1))

num = uint8
120