list<string> FileNamesPatternsList; // In this list there are about 100 files
vector<string> FilesToBeSearched;   // In this vector there are about 300 files

list<string>::iterator compareIterator;
vector<string>::iterator compareIterator2;

for( compareIterator = FileNamesPatternsList.begin(); compareIterator != FileNamesPatternsList.end(); compareIterator++){
for( compareIterator2 = FilesToBeSearched.begin(); compareIterator2 != FilesToBeSearched.end(); compareIterator2++)
            {
                smatch result;
                if(regex_search(*compareIterator2,result,regex(*compareIterator))){
                MyFilewithResults << "File: " << result[0] << "fit to" << *compareIterator2 << endl;
                }
            }

    }