By some reason, I could not quickly find C++ implementation of the algorithm for you. I think you can better help yourself by doing your own search.
So far, I got too ideas:
1) You can use this C# implementation:
Aho-Corasick string matching in C#[
^]. I have no idea how good is this one, but you can give it a try. Translation in C++ is not such a big problem.
2) The Wikipedia article (
http://en.wikipedia.org/wiki/Aho–Corasick_string_matching_algorithm[
^]) says that the Aho–Corasick string matching algorithm formed the basis of the original Unix command
fgrep (
http://en.wikipedia.org/wiki/Grep#Variations[
^]). You could download Unix source code for this application and find the algorithm implementation there. See other references on these Wikipedia articles.
—SA