uninitialized_copy

将指定源范围中的对象复制到未初始化的目标范围。

template<class InputIterator, class ForwardIterator> 
   ForwardIterator uninitialized_copy( 
      InputIterator _First,  
      InputIterator _Last, 
      ForwardIterator _Dest 
   );

参数

• _First
  确定源范围中第一个元素的地址的输入迭代器。

• _Last
  确定源范围中最后一个元素的地址的输入迭代器。

• _Dest
  确定目标范围中第一个元素的地址的前向迭代器。

返回值

确定超出目标范围的第一个位置的地址的前向迭代器，除非源范围为空，此时迭代器将确定 _First 的地址。

备注

该算法可将内存分配与对象构造分离开。

该模板函数有效执行以下操作：

while ( _First!= _Last )
   new ( ( void * )&*_Dest ++)
      iterator_traits<InputIterator>::value_type ( *_First ++ );
return _First;

除非代码引发异常。 在这种情况下，所有构造的对象将销毁，并重新引发异常。

示例

// memory_uninit_copy.cpp
// compile with: /EHsc /W3
#include <memory>
#include <iostream>

using namespace std;

   class Integer 
   {
   public:
      Integer( int x ) : val( x ) {}
      int get( ) { return val; }
   private:
      int val;
   };

int main( )
{
   int Array[] = { 10, 20, 30, 40 };
   const int N = sizeof( Array ) / sizeof( int );

   int i;
   cout << "The initialized Array contains " << N << " elements: ";
      for (i = 0 ; i < N; i++ )
      {
         cout << " " << Array [ i ];
      }
   cout << endl;

   Integer* ArrayPtr = ( Integer* ) malloc( N * sizeof( int ) );
   Integer* LArrayPtr = uninitialized_copy(
      Array, Array + N, ArrayPtr);  // C4996

   cout << "Address of position after the last element in the array is: " 
        << &Array[0] + N << endl;
   cout << "The iterator returned by uninitialized_copy addresses: " 
        << ( void* )LArrayPtr << endl;
   cout << "The address just beyond the last copied element is: " 
        << ( void* )( ArrayPtr + N ) << endl;

   if ( ( &Array[0] + N ) == ( void* )LArrayPtr )
      cout << "The return value is an iterator "
           << "pointing just beyond the original array." << endl;
   else
      cout << "The return value is an iterator "
           << "not pointing just beyond the original array." << endl;

   if ( ( void* )LArrayPtr == ( void* )( ArrayPtr + N ) )
      cout << "The return value is an iterator "
           << "pointing just beyond the copied array." << endl;
   else
      cout << "The return value is an iterator "
           << "not pointing just beyond the copied array." << endl;

   free ( ArrayPtr );

   cout << "Note that the exact addresses returned will vary\n"
        << "with the memory allocation in individual computers."
        << endl;
}

示例输出

The initialized Array contains 4 elements: 10 20 30 40
Address of position after the last element in the array is: 0012FED8
The iterator returned by uninitialized_copy addresses: 00311B88
The address just beyond the last copied element is: 00311B88
The return value is an iterator not pointing just beyond the original array.
The return value is an iterator pointing just beyond the copied array.
Note that the exact addresses returned will vary
with  the memory allocation in individual computers.

要求

标头：<memory>

命名空间: std