Variable file path for importdata

I am unsure why the following code does not work:

str = input('Enter the filename: ', 's');
bottom_temp = fullfile('Temperatures','Bottom',str,'.txt');
BOT_TEMP = importdata(bottom_temp);

But this code does work:

BOT_TEMP = importdata('Temperatures\Bottom\str.txt');
% where str is the name of the file

The first set of code returns: 'Unable to open file'

I have a feeling that there is some simple formatting error that I am overlooking, any help would be appreciated.

Answer 1

[Azzi Abdelmalek]

bottom_temp = fullfile('Temperatures','Bottom',[str,'.txt'])