Undefined function 'substring' for input arguments of type 'char'. Error in extract_db (line 45) file_a = substring(char(file_a), 0, findstr(char(file_a), '_')-2);

What is the substitute function to evaluate file_a = substring(char(file_a), 0, findstr(char(file_a), '_')-2); because this function is not executing in matlab 2016

   %%
files = dir('E:\MATLAB\R2016b\bin\img\PCA\my_PhD_Programs\minuite\sc_minutia\Db1_a\*.tif');
 cd  'E:\MATLAB\R2016b\bin\img\PCA\my_PhD_Programs\minuite\sc_minutia\Db1_a';

  IMPRESSIONS_PER_FINGER=8;
  file_names = {files.name};

  index1 = 1;
  while index1 <= 1          %80
    finger_features=struct('X', [], 'M', [], 'O', [], 'R', [], 'N', [], 'RO',[], 'OIMG', [], 'OREL', []); 

    for i=0:IMPRESSIONS_PER_FINGER-1
            finger_features = extract_finger(char(file_names(index1 + i)));
     
       file_a = file_names(index1 + i);
            fOut = sprintf('%s.X', char(file_a));
            csvwrite(fOut, finger_features.X);
            fOut = sprintf('%s.m', char(file_a));
          csvwrite(fOut, finger_features.M);
          fOut = sprintf('%s.o', char(file_a));
          csvwrite(fOut, finger_features.O);
          fOut = sprintf('%s.r', char(file_a));
          csvwrite(fOut, finger_features.R);
          fOut = sprintf('%s.n', char(file_a));    
   
       csvwrite(fOut, finger_features.N); 
          fOut = sprintf('%s.ro', char(file_a));                                           
          csvwrite(fOut, finger_features.RO);   
          fOut = sprintf('%s.oi', char(file_a));                                           
          csvwrite(fOut, finger_features.OIMG);   
          fOut = sprintf('%s.or', char(file_a));                                           
          csvwrite(fOut, finger_features.OREL);   
        end
    
      file_a = file_names(index1);
      file_a = substring(char(file_a), 0, findstr(char(file_a), '_')-2);   
     
      index1 = index1 + IMPRESSIONS_PER_FINGER;
      end

[Stephen23]

You appear to be storing your user files in the MATLAB installation folder:

'E:\MATLAB\R2016b\bin\img\PCA\my_PhD_Programs\minuite\sc_minutia\Db1_a\*.tif'

User data should never be stored in any application's installation folder.

Answer 1

[madhan ravi]

AFAIK: There is no such syntax as substring() in matlab

see

https://www.mathworks.com/help/matlab/ref/extractafter.html

https://www.mathworks.com/help/matlab/ref/extractbetween.html

[Walter Roberson]

note those require r2016b or later .

[madhan ravi]

Thank you sir Walter for mentioning it.

[Walter Roberson]

There is a MuPad substring function but it would be a nuisance to use from matlab proper.

There is a java substring but it would not work on char arguments .

[madhan ravi]

The second information is new to me sir Walter thank you :)