identifying positions of a string within a text file

5 views (last 30 days)
I would like to take a text file, which has been saved with various special characters ('e.g. $$') and identify the positions that these characters occupy. Then, I would insert values into those positions. So the file may look like: line $$ 1 $$ line 2
So I would need some way to identify positions 6 and 11, then insert text at those locations.
I've tried various things such as reading the file in a string and converting to a char array while using strfind, but in each case, there is an issue. What would be the best way to overwrite the $$'s with values?
Thanks

Accepted Answer

Walter Roberson
Walter Roberson on 1 Mar 2011
Probably something like this:
fid = fopen(FileName,'rt');
filetext = fread(fid,'*char');
fclose(fid);
newtext = regexprep(filetext, '\$\$', 'Hello', 'once');
newtext = regexprep(newtext, '\$\$', 'World', 'once');
fid = fopen(NewFilename, 'wt');
fwrite(fid, newtext, '*char');
fclose(fid);

More Answers (2)

Brett Shoelson
Brett Shoelson on 1 Mar 2011
Lots of ways. This one uses regular expressions:
mystr = 'line $$ 1 $$ line 2'
newstr = regexprep(mystr,'\$\$','New_String')
Cheers,
Brett

Brent
Brent on 1 Mar 2011
Thank you both for the quick reply. This is exactly what I needed.

Categories

Find more on Characters and Strings in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!