Challanges representing hexadecimal values as "integer double" in uitable
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In a uitable, I’m editing multiple cells and I want to use hexadecimal (integer) as the input value. For most cases this turns out perfectly fine. However, hexadecimal values ending with 'e' are causing me a headache. It seems that Matlab interprets the input as string and converts the hexadecimal input (0xXXXX, without quotation marks) using ‘str2double’ before any callbacks are triggered. ‘str2double’ uses ‘sscanf’ behind the scenes and in ‘str2double’, ‘sscanf’ is called with format specifier ‘%f’. This makes sense when ‘str2double’ tries to convert to a double value. When ‘sscanf’ is called with ‘%f’, it probably triggers on the trailing ‘e’ for scientific notation. There is no value proceeding ‘e’ and ‘str2double’ fails to read the entire char-array and returns NaN.
I am able to catch the NaN-value and re-evaluate the string using ‘myStr2double’, where I call ‘sscanf’ with format specifier ‘%i’. This works, but it seems like an unnecessary step as not doing this works for all hexadecimal values (I’ve tested) except for those ending with ‘e’.
Here are some sample code to illustrate the problem:
str2double('0x1234')
returns 4660 (as expected)
str2double('0x123e')
returns NaN.
Is there a better solution to this behaviour, or am I trying to do something that is just outside of the intention?
In ‘myStr2double’, i call:
[a,count,errmsg,nextindex] = sscanf(s,'%i',1)
to read the entire hexadecimal char-array.
3 Comments
Stephen23
on 18 Dec 2021
Edited: Stephen23
on 18 Dec 2021
"...am I trying to do something that is just outside of the intention?"
Yes. STR2DOUBLE is not documenented to convert hexadecimal numbers. For reliable conversion use functions which are designed and documented for converting hexadecimal, e.g. HEX2DEC, SSCANF.
Answers (1)
Voss
on 18 Dec 2021
Maybe using hex2dec instead of str2double will work:
str2double('0x1234')
str2double('0x123e')
hex2dec('0x1234')
hex2dec('0x123e')
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