这是三分之二insert
来自 std::vector 的方法签名:
void insert (iterator position, size_type n, const value_type& val);
template <class InputIterator>
void insert (iterator position, InputIterator first, InputIterator last);
现在,给定一个向量和一个插入调用,
std::vector<int> v;
v.insert( v.begin(), 3, 3 );
怎么第一个insert
选择的是第一个而不是第二个?
我确信我天真地实现了相同的签名,但这里编译器选择了第二种(模板化)形式。
template <class T, int MAXSIZE>
class svector {
public:
class iterator : public std::iterator<std::input_iterator_tag,T> { ... };
// ...
void insert (class iterator position, size_t n, const T& val){
if( len + n > MAXSIZE ) throw std::out_of_range( "insert exceeds MAXSIZE" );
uint32_t iPos = position - begin();
uint32_t movlen = len - iPos + 1;
for( uint32_t i = 0; i < movlen; i++ ){
ele[len + n - i] = ele[len - i];
}
for( uint32_t i = 0; i < n; i++ ){
ele[iPos + i] = val;
}
len += n;
}
template <class InputIterator>
void insert (class iterator position, InputIterator first, InputIterator last){
for( InputIterator it = first; it != last; it++ ){
if( len + 1 > MAXSIZE ) throw std::out_of_range( "insert exceeds MAXSIZE" );
*position = *reinterpret_cast<T*>( it );
}
}