# MATLAB: Variable file path for importdata

file pathimportdatavariable file path

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.

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