how to subtract the contents of two strings

[Junhui Liao]

Dear all,

In my code, I read from a file then write in multiple files.
In each of these multiple files, there are two columns , to
the first column, I hope every lines of this column could subtract
the first line.

For instance,
the original data in a file is like:

1.0E-08 , 2.3E-02
1.1E-08 , 2.8E-02
1.2E-08 , 3.1E-02

.......


I hope after my script running, the content of the modified file like this:

0.0E-08 , 2.3E-02
0.1E-08 , 2.8E-02
0.2E-08 , 3.1E-02

.......

The data in the file is in string format.

Does anybody has any suggestions?

Thanks a lot in advance!

Best regards,
Junhui

[mcleano]

http://www.cplusplus.com/articles/numb_to_text/#s2n

[Junhui Liao]

Hi, mcleano,

This is the link I was looking for ! : )

Thanks you very much for your information
and also to the author of the article.

Best regards,
Junhui