Comments on: Using Gcc C++ Hash Classes With Strings http://www.moosechips.com/2008/10/using-gcc-c-hash-classes-with-strings/ leaving my mark on the internet Sun, 01 Jan 2012 16:09:23 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: David http://www.moosechips.com/2008/10/using-gcc-c-hash-classes-with-strings/comment-page-1/#comment-214 David Thu, 30 Jun 2011 18:36:00 +0000 http://www.moosechips.com/?p=387#comment-214 mmm... something strange happend when I wrote my comment...  My question is about hash functions for unsigned long long int type! mmm… something strange happend when I wrote my comment…  My question is about hash functions for unsigned long long int type!

]]> By: David http://www.moosechips.com/2008/10/using-gcc-c-hash-classes-with-strings/comment-page-1/#comment-213 David Thu, 30 Jun 2011 18:34:00 +0000 http://www.moosechips.com/?p=387#comment-213 Hi! I've been looking for a long time how to add hash support to my old gcc version! Now I am facing a new problem : how can I add hash support ? Thanks in advance! Hi! I’ve been looking for a long time how to add hash support to my old gcc version! Now I am facing a new problem : how can I add hash support ? Thanks in advance!

]]> By: MLRUS http://www.moosechips.com/2008/10/using-gcc-c-hash-classes-with-strings/comment-page-1/#comment-50 MLRUS Mon, 17 Aug 2009 03:04:31 +0000 http://www.moosechips.com/?p=387#comment-50 Thank you for this example. I have a more complex template usage, and your example showed me that I simply have to dereference the iterator to get the results back. I suppose I should add a typedef to make things readable, since now I have the following "easy to read" code: for( __gnu_cxx::_Hashtable_const_iterator<const char*, const char*, __gnu_cxx::hash, std::_Identity, Dictionary::eqstr, std::allocator > xit = dictionary.words.begin(); xit != dictionary.words.end(); xit++) { cout << *xit << endl; } class Dictionary: public Storable { struct eqstr { bool operator()(const char* s1, const char* s2) const { return strcmp(s1, s2) == 0; } }; __gnu_cxx::hash_set<const char*,__gnu_cxx:: hash, eqstr> words; inline const bool lookup(const __gnu_cxx::hash_set<const char*, __gnu_cxx::hash, eqstr>& words, const char* word) { __gnu_cxx::hash_set<const char*, __gnu_cxx::hash, eqstr>::const_iterator it = words.find(word); return it!=words.end(); } inline const bool lookup(const string& word) { return lookup(words,word.c_str()); } inline const bool lookup(const char *word) { return lookup(words,word); } public: inline const bool contains(const string &entry) { return lookup(entry); } inline const bool contains(const char *entry) { return lookup(entry); } void clear() { words.clear(); } inline int wordCount() { return words.size(); } void read(const std::string &filename) { try { ifstream infile(filename.c_str(), std::ios_base::in); string line; while (getline(infile, line, '\n')) { Util::trim(line); Util::upperCase(line); words.insert(strdup(line.c_str())); } infile.close(); } catch (...) { cerr << "Error reading " << filename << endl; } } Dictionary() : words() { } Dictionary(string &filename) : words() { read(filename); } virtual ~Dictionary() { words.clear(); } }; Thank you for this example. I have a more complex template usage, and your example showed me that I simply have to dereference the iterator to get the results back. I suppose I should add a typedef to make things readable, since now I have the following “easy to read” code:

for( __gnu_cxx::_Hashtable_const_iterator<const char*, const char*, __gnu_cxx::hash,
std::_Identity, Dictionary::eqstr, std::allocator >
xit = dictionary.words.begin(); xit != dictionary.words.end(); xit++) {
cout << *xit << endl;
}

class Dictionary: public Storable {
struct eqstr
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) == 0;
}
};

__gnu_cxx::hash_set<const char*,__gnu_cxx:: hash, eqstr> words;

inline const bool lookup(const __gnu_cxx::hash_set<const char*, __gnu_cxx::hash, eqstr>& words,
const char* word)
{
__gnu_cxx::hash_set<const char*, __gnu_cxx::hash, eqstr>::const_iterator it = words.find(word);
return it!=words.end();
}

inline const bool lookup(const string& word) {
return lookup(words,word.c_str());
}

inline const bool lookup(const char *word) {
return lookup(words,word);
}

public:

inline const bool contains(const string &entry) {
return lookup(entry);
}

inline const bool contains(const char *entry) {
return lookup(entry);
}

void clear() {
words.clear();
}

inline int wordCount() {
return words.size();
}

void read(const std::string &filename) {
try {
ifstream infile(filename.c_str(), std::ios_base::in);
string line;
while (getline(infile, line, ‘\n’)) {
Util::trim(line);
Util::upperCase(line);
words.insert(strdup(line.c_str()));
}
infile.close();
} catch (…) {
cerr << “Error reading ” << filename << endl;
}
}

Dictionary() :
words() {

}
Dictionary(string &filename) :
words() {
read(filename);
}

virtual ~Dictionary() {
words.clear();
}
};

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