read a particular string from a line in text file

Question

Rakesh Praveen 2015-9-2

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/239170-read-a-particular-string-from-a-line-in-text-file

回答： Tom Wright 2015-9-2

采纳的回答： Tom Wright

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 ?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Tom Wright 2015-9-2

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/239170-read-a-particular-string-from-a-line-in-text-file#answer_191102

在 MATLAB Online 中打开

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