String indexing in MATLAB: single vs. double quote

Question

I have a matrix of strings such as the following:

readFiles = [   
            "11221", "09";
            "11222", "13";
            "12821", "06";
            "13521", "02";
            "13522", "13";
            "13711", "05";
            "13921", "01";
            "14521", ".001";
            "15712", ".003"
            ];

These are used to access to some folders and files in an automatic way. Then what I want to do is the following (with ii being some integer):

FileName = strcat('../../Datasets/hc-1/d',readFiles(ii,1),'/d',...
                     readFiles(ii,1),readFiles(ii,2),'.dat');
data(ii,:) = LoadBinary(FileName, 6);

The string FileName is then generated using double quotes (I'm not sure why). So its value is:

FileName = 

"../../Datasets/hc-1/d13921/d1392101.dat"

The function LoadBinary() returns an error when trying to perform the following operation:

lastdot = strfind(FileName,'.');
FileBase = FileName(1:lastdot(end)-1); % This line 

However, if I create the string FileName manually using single quotes, the function works okay.

In a nutshell, if I try to index a string (FileName(1:lastdot(end)-1)) that is created with the lines above (leading to FileName = "../../Datasets/hc-1/d13921/d1392101.dat"), MATLAB returns an error. If I create it manually with single quotes (FileName = '../../Datasets/hc-1/d13921/d1392101.dat'), the function works right.

Why does this happen? Is there a way to fix it (i.e. convert the double-quoted string into a single-quoted one)?

Answer 1

Double quotes are String array, while Single one are Char array. You can convert your string array to a char one using the function char. So you'd write :

CharFileName = char(FileName)

And it should resolve your issue.