Getting this error : Operator '==' is not supported for operands of type 'cell'. what should I do?

function [ output_array ] = Klammer_Koordinate_Trennung( input_str )

for i= 1:length(input_str)
    if input_str(i) == '('
       index_1 = i;
    end  
    
    if input_str(i) == ','
       index_2 = i; 
    end  
     
    if input_str(i) == ')'
       index_3 = i;
       break; 
    end    
end

output_array = [str2num(input_str(index_1 + 1 :index_2 - 1)),...
    str2num(input_str(index_2 + 1 : index_3 - 1 ))];

end

Answer 1

[Torsten]

https://uk.mathworks.com/help/stateflow/ref/strcmp.html

Answer 2

[Dirk Engel]

Your function is designed to work when the input argument is a char vector, e.g. '(1,2)', but the error indicates that your function instead gets called with a cell array, e.g., {'(1,2)'}.

If the cell array contains a single char vector, you could add the following line to the top of your function to extract the char vector from the cell:

if iscell(input_str)
    input_str = input_str{1}
end

If the cell arrray contains multiple elements, consider a second outer loop over the elements of the cell array.

Note that there are builtin ways to extract numbers from formatted text, such as sscanf() or textscan(). E.g.,

sscanf('(1.1,2.2)', '(%f,%f)', [1, 2])

extracts [1.1, 2.2] from the formatted string.

Answer 3

[Michael Hubatka]

Use regular expressions, for example

str2double(regexp("(1, 2)", "\d+", "match"))

ans = 1×2

1 2

for integer only and

str2double(regexp("(1.2, 3)", "\d+\.?\d*", "match"))

ans = 1×2

1.2000 3.0000

for floating point and integers.