c++ - Erasing a struct element within a list -

what trying remove element list. elements structs. having difficult time this. examples online not struct elements. tried set key/values default values once iterate through data prints white space meaning element still there. need remove completely. below code.

.h file

#include<list> #include<queue> using namespace std;  template <typename k, typename v, int cap> class hashtable { public:     hashtable(int(*)(const k&));     bool hashtable<k, v, cap>::containskey(const k& key) const;     hashtable<k, v, cap>& operator=(const hashtable<k, v, cap>&);     v& operator[](const k&); // setter     v operator[](const k&) const;  // getter     queue<k> keys() const;     int size() const {return siz;};     void deletekey(const k&);  private:      int getindex(const k& key) const;     struct node{k key; v value;};      int(*hashcode)(const k&);     list<node> data[cap];     int cap;     int siz; }; 

here delete function trying implement.

template<typename k, typename v, int cap> inline void hashtable<k, v, cap>::deletekey(const k & key) {   typename list<node>::iterator it; // getters need use const_iterator   (int = 0; < cap; i++)   {     (it = data[i].begin(); != data[i].end(); it++)     {       if (it->key == key)       {         // these few things tried, know not right.          data[i].back().key = k();          data[i].back().value = v();          data[i].remove(key); // error  c2664   'void std::list<hashtable<std::string,int,100>::node,std::allocator<_ty>>::remove(const _ty &)':                               // cannot convert argument 1 'const std::string' 'const hashtable<std::string,int,100>::node &'   10hashtable       }     }   } } 

key std::string, list contains nodes.
also, data[i].back() last element of list , not *it.

you use erase remove element iterator corresponds to:

template<typename k, typename v, int cap> inline void hashtable<k, v, cap>::deletekey(const k & key) {   (int = 0; < cap; i++)   {     typename list<node>::iterator = data[i].begin();     while (it != data[i].end())     {       if (it->key == key)       {          // make 'it' valid iterator next element          = data[i].erase(it);       }       else       {          // increment if didn't erase          it++;       }     }   } } 

these days, c++11, following should enough:

template<typename k, typename v, int cap> inline void hashtable<k, v, cap>::deletekey(const k & key) {   (auto& bucket: data)   {       bucket.remove_if([&] (auto& item) { return item->key == key; });   } } 

but since hashtable, presumably index in data hash of key, turn one-liner:

template<typename k, typename v, int cap> inline void hashtable<k, v, cap>::deletekey(const k & key) {     data[hashcode(key)].remove_if([&] (auto& item) { return item->key == key; }); } 

or, since need find 1 element (your keys map 1 value), can longer more efficient:

template<typename k, typename v, int cap> inline void hashtable<k, v, cap>::deletekey(const k & key) {     auto& bucket = data[hashcode(key)];     auto = std::find_if(bucket.begin(),                             bucket.end(),                             [&] (auto& item) { return item->key == key; });     if (it != bucket.end())     {         bucket.erase(it);     } }