it says error using assert, assertion failed and error in iuntitled (line 10) assert(ischar(in))

error using assert

Assertion failed

Error in iuntitled (line 10)

assert(ischar(in))

[Geoff Hayes]

@Ian - did you add the assert? Or is it being called from some other piece of code? If other code, can you post the code to this question?

If in is not a character, then ischar(in) will be false and the assert is indicating this. See assert for details on how this function behaves with false input parameter.

[Ian]

heres the code

function result = encodeCharacter(in) 
% Encode a single character into the 16-bit sequence for the Code 39 
% barcode format. 
% 
% Rupert Thomas, March 2016 
% 
% Thanks to (for the codes): % http://notionovus.com/blog/code-39-barcode-biscuits/#setup 

assert(ischar(in));
assert(length(in)==1);

codesArray = { 
    '1010001110111010', '1110100010101110', '1011100010101110', '1110111000101010', ... % 0, 1, 2, 3 
    '1010001110101110', '1110100011101010', '1011100011101010', '1010001011101110', ... % 4, 5, 6, 7 
    '1110100010111010', '1011100010111010', '1110101000101110', '1011101000101110', ... % 8, 9, A, B 
    '1110111010001010', '1010111000101110', '1110101110001010', '1011101110001010', ... % C, D, E, F 
    '1010100011101110', '1110101000111010', '1011101000111010', '1010111000111010', ... % G, H, I, J 
    '1110101010001110', '1011101010001110', '1110111010100010', '1010111010001110', ... % K, L, M, N 
    '1110101110100010', '1011101110100010', '1010101110001110', '1110101011100010', ... % O, P, Q, R 
    '1011101011100010', '1010111011100010', '1110001010101110', '1000111010101110', ... % S, T, U, V 
    '1110001110101010', '1000101110101110', '1110001011101010', '1000111011101010', ... % W, X, Y, Z 
    '1000101011101110', '1110001010111010', '1000111010111010', '1000100010001010', ... % -, ., (space), $ 
    '1000100010100010', '1000101000100010', '1010001000100010', '1000101110111010'}; ... % /, +, %, *
    strCode39 = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. $/+%*'; 
    
    idx = strfind(strCode39,upper(in)); % Force to upper case 
    if any(idx)
        result = codesArray{idx}; 
    else 
        error('Invalid input - character not part of the Code 39 set'); 
    end 
end

[Ian]

can you help me with this

Answer 1

[Geoff Hayes]

@Ian - as per the function comment, Encode a single character i. I suspect that you are passing something else i.e. a numeric value like

>> encodeCharacter(42)
Error using encodeCharacter (line 8)
Assertion failed.

Try doing

>> encodeCharacter('4')

ans =

    '1010001110101110'

or any other character. Note that you can only pass in one character. If you pass in 2 or more, then a different assert will fire.

Answer 2

[Cris LaPierre]

That is what an assert does. If the assertion fails (here that means that in is not a char), then an error is thrown and the message 'Assertion failed.' is thrown.

% Assertion is true -> no error
in = '5';
assert(ischar(in))

% Assertion is false -> error
in = 5;
assert(ischar(in))

Error using assert
Assertion failed.

[Daniel Lyddy]

I hate the fact that it prints "Error using assert." That misleads developers into thinking they've coded up their assert() lines incorrectly.

I just want to print my own error message. The other stuff is confusing to my end users, and should only be printed as a default if I have not provided my own error message.

[Stephen23]

@Daniel Lyddy: it is also strangely inconsistent: ERROR does not state "Error using error":

error('some text')

some text

MATLAB versions until at least R2021a did not include the text "Error using assert", so it is a recent change:

Apparently someone meddled in something that worked perfectly. My guess is that new text was introduced with this behavior change in R2022a:

https://www.mathworks.com/help/matlab/release-notes.html?rntext=assert&startrelease=R2022a&endrelease=R2023b&groupby=release&sortby=descending&searchHighlight=assert

A related topic, where someone meddled with ERROR to try and "improve" it... thus rendering it useless:

https://www.mathworks.com/matlabcentral/answers/1814220-calling-the-error-function-does-not-print-the-line-number-in-r2022b