My post below asked what the curly quotation marks were and why my app wouldn't work with them, my question now is how can I replace them when my program comes across them, how can I do this in C#? Are they special characters?
curly-quotation-marks-vs-square-quotation-marks-what-gives
Thanks
I have a whole great big... program... that does precisely this. You can rip out the script and use it at your leasure. It does all sorts of replacements, and is located at http://bitbucket.org/nesteruk/typografix
Note that what you have is inherently a corrupt CSV file. Indiscriminately replacing all typographer's quotes with straight quotes won't necessarily fix your file. For all you know, some of the typographer's quotes were supposed to be there, as part of a field's value. Replacing them with straight quotes might not leave you with a valid CSV file, either.
I don't think there is an algorithmic way to fix a file that is corrupt in the way you describe. Your time might be better spent investigating how you come to have such invalid files in the first place, and then putting a stop to it. Is someone using Word to edit your data files, for instance?
To extend on Nick van Esch's popular answer, here is the code with the names of the characters in the comments.
When I encountered this problem I wrote an extension method to the String class in C#.
This simply replaces the silly 'smart quotes' with normal quotes.
[EDIT] Fixed to also support replacement of 'double smart quotes'.
Using Nick and Barbara's answers, here is example code with performance stats for 1,000,000 loops on my machine:
Time: 958.1011 milliseconds
Time: 362.0858 milliseconds
A more extensive listing of problematic word characters