当我尝试编写这样的代码时,我得到了这个编译错误。实际上,运算符 [ ] 是重载的。我很困惑,有人可以帮助我吗?
AssocArray<int, int> ary;
ary.addItem(1, 1);
ary.addItem(2, 1);
ary.addItem(3, 1);
ary.addItem(4, 1);
ary.addItem(5, 1);
ary[5] = 2;//error occur here
这是错误消息:
error C2679: binary '[' : no operator found which takes a right-hand operand of type 'int' (or there is no acceptable conversion)
...could be 'int &opt::AssocArray<key,value>::operator [](key &)'
with
[
key=int,
value=int
]
while trying to match the argument list '(opt::AssocArray<key,value>, int)'
with
[
key=int,
value=int
]
AssocArray 的实现如下(注意:它位于 *.h 文件中):
template <typename key, typename value>
class AssocArray
{
public:
typedef typename std::pair<key, value> type;
bool addItem(key& k, value& v);
bool addItem(key k, value v);
bool isItem(key& k);
value& operator[] (key& k);
typename std::vector<type>::iterator begin()
{
return vecData.begin();
}
typename std::vector<type>::iterator end()
{
return vecData.end();
}
protected:
private:
std::vector<type> vecData;
};
template <typename key, typename value>
bool AssocArray<key, value>::addItem( key k, value v )
{
if(isItem(k)) return false;
vecData.push_back(std::make_pair(k, v));
return true;
}
template <typename key, typename value>
value& AssocArray<key, value>::operator[]( key& k )
{
auto iter = std::find_if(vecData.begin(), vecData.end(),
[&](type& param)
{
return param.first == k;
}
);
if(vecData.end() != iter)
return iter->second;
value v;
vecData.push_back(std::make_pair(k, v));
return vecData.rbegin()->second;
}
template <typename key, typename value>
bool AssocArray<key, value>::isItem( key& k )
{
auto iter = std::find_if(vecData.begin(), vecData.end(),
[&](type& param) mutable -> bool
{
return param.first == k;
}
);
return vecData.end() != iter;
}