Putting I(k) in quotes makes Matlab read it as a char instead of a variable. It is literally looking for I(k).mp4. To use the value of I(k), simply put (note the double quotes):
aFile = fullfile(Folder, I(k) + ".mp4");
Matlab automatically converts the number in I(k) into a string for addition. (But, doesn't do the same for adding to a char like '.mp4')
But, there's actually a way to simplify your code a bit, since you can directly index into the strng char:
clc;
clear all;
close all;
number=45;
strng=num2str(number);
Folder = 'D:\project\Fingerspelling pics\';
for k=1:length(strng)
aFile = fullfile(Folder, [strng(k) '.mp4']);
videoFReader = vision.VideoFileReader(aFile);
videoPlayer = vision.VideoPlayer;
while ~isDone(videoFReader)
frame = step(videoFReader);
step(videoPlayer,frame);
end
end
Here, the addition is done by concatenating chars..
