Matrix Dimensions must agree

I am getting this error at line 25 for the code:

clc
clear all
i=1;
b=int64(nan(848,896));
c=int64(nan(848,896));
for i=1:9999
    if i<10
        new="0000";
    elseif i<100
        new="000";
    elseif i<1000
        new="00";
    elseif i<10000
        new="0";
    end
    i2=new + num2str(i);
    path='C001H001S00040'+i2 + '.tif';
    a=int64(imread(path));
    disp(i2)
    i=i+1;
    b=b+a;
end
for k=10000:15068
    i3=num2str(k);
    path_new='C001H001S00040'+i3 + '.tif';
    a=int64(imread(path_new));
    disp(i3)
    k=k+1;
    c=c+a;
end
b=(b+c)/15068;
b=uint8(b);
imshow(b)

Error:
Error in new_code (line 25)
    path_new='C001H001S00040'+i3 + '.tif';

Answer 1

[dpb]

The + operator only works for the class string catenation, not character strings.

    path_new="C001H001S00040" + i3 + ".tif";

and will still only work if i3 is also of class string.