read a particular string from a line in text file

Lets say I have two lines in a text file like this:

The value of the number is 240.56 units.

The value of the number is 140.43 units.

I want to read only the values (240.56 and 140.43) from those lines. However there are many such lines in the similar format inside the text file. So i can't go by comparing string value and then read that value. How to read those dynamic values which are located in a sentence at a particular position. Any ideas ?

Answer 1

[Tom Wright]

Sounds like a regular expression is the way to go.

fid = fopen('YourFile.txt','rt');

expression = '([\d.]+)' % matches one or more digits and .
% a more advanced expression is (\d+(?:\.\d*)?|\.\d+)

while true
  thisline = fgetl(fid);
  value = regexp(thisline,exp,'match'); % perform the regular expression
  value = value(0);
end