所以我试图通过使用boost :: ptr_vector来摆脱我的std :: vector.现在我正在尝试从一个元素中删除一个元素,并删除已删除的元素.对我来说最明显的事情是：
class A
{ int m; };
boost::ptr_vector<A> vec;
A* a = new A;
vec.push_back(a);
vec.erase(a);
但这甚至不会编译(请参阅下面的完整错误消息).我已经尝试过删除/删除习惯用法,就像我在std :: vector上所做的那样,但是boost :: ptr_vector的所有算法都与std :: vector中的算法略有不同.
所以我的问题：
>如何从ptr_vector中删除指针？
>我还需要手动删除()我删除的元素吗？
编译错误：
1>------ Build started: Project: ptr_vector_test,Configuration: Debug Win32 ------ 1>Compiling... 1>ptr_vector_test.cpp 1>c:\users\rvanhout\svn\trunk\thirdparty\boost\range\const_iterator.hpp(37) : error C2825: 'C': must be a class or namespace when followed by '::' 1> c:\users\rvanhout\svn\trunk\thirdparty\boost\mpl\eval_if.hpp(63) : see reference to class template instantiation 'boost::range_const_iterator<C>' being compiled 1> with 1> [ 1> C=A * 1> ] 1> c:\users\rvanhout\svn\trunk\thirdparty\boost\range\iterator.hpp(63) : see reference to class template instantiation 'boost::mpl::eval_if_c<C,F1,F2>' being compiled 1> with 1> [ 1> C=true,1> F1=boost::range_const_iterator<A *>,1> F2=boost::range_mutable_iterator<A *const > 1> ] 1> c:\users\rvanhout\svn\trunk\thirdparty\boost\ptr_container\detail\reversible_ptr_container.hpp(506) : see reference to class template instantiation 'boost::range_iterator<C>' being compiled 1> with 1> [ 1> C=A *const 1> ] 1> c:\tmp\ptr_vector_test\ptr_vector_test.cpp(21) : see reference to function template instantiation 'boost::void_ptr_iterator<VoidIter,T> boost::ptr_container_detail::reversible_ptr_container<Config,CloneAllocator>::erase<A*>(const Range &)' being compiled 1> with 1> [ 1> VoidIter=std::_Vector_iterator<void *,std::allocator<void *>>,1> T=A,1> Config=boost::ptr_container_detail::sequence_config<A,std::vector<void *,std::allocator<void *>>>,1> CloneAllocator=boost::heap_clone_allocator,1> Range=A * 1> ] 1>c:\users\rvanhout\svn\trunk\thirdparty\boost\range\const_iterator.hpp(37) : error C2039: 'const_iterator' : is not a member of '`global namespace'' 1>c:\users\rvanhout\svn\trunk\thirdparty\boost\range\const_iterator.hpp(37) : error C2146: Syntax error : missing ';' before identifier 'type' 1>c:\users\rvanhout\svn\trunk\thirdparty\boost\range\const_iterator.hpp(37) : error C2208: 'boost::type' : no members defined using this type 1>c:\users\rvanhout\svn\trunk\thirdparty\boost\range\const_iterator.hpp(37) : fatal error C1903: unable to recover from prevIoUs error(s); stopping compilation 1>Build log was saved at "file://c:\tmp\ptr_vector_test\Debug\BuildLog.htm" 1>ptr_vector_test - 5 error(s),0 warning(s) ========== Build: 0 succeeded,1 Failed,0 up-to-date,0 skipped ==========
解决方法
那么你可以用std :: vector做到这一点.
在这两种情况下,erase都将迭代器作为参数.
因此,在您从矢量(或ptr_vector)中删除某些内容之前,您需要找到它.
另请注意,ptr_vector将其内容视为已存储对象而非存储指针.所以任何搜索都是通过对象完成的.
所以基本上
std::vector<A> x; std::ptr_vector<A> y; // These two object should behave in exactly the same way. // The ONLY difference is inserting values which for y are pointers. // Y take ownership of the pointer and all subsequent acesses to the // members of y look like they are objects
例：
#include <boost/ptr_container/ptr_vector.hpp>
#include <vector>
class A
{ int m;
public:
A(int x):m(x) {}
bool operator==(A const& rhs) {return m = rhs.m;}
};
int main()
{
boost::ptr_vector<A> x;
x.push_back(new A(1));
x.erase(std::find(x.begin(),x.end(),A(1)));
std::vector<A> y;
y.push_back(A(2));
y.erase(std::find(y.begin(),y.end(),A(2)));
// To find an exact pointer don't modify the equality.
// Use find_if and pass a predicate that tests for a pointer
A* a = new A(3);
boost:ptr_Vector<A> z;
z.push_back(a);
z.erase(std::find_if(y.begin(),CheckPointerValue(a));
}
struct CheckPointerValue
{
CheckPointerValue(A* a):anA(a) {}
bool operator()(A const& x) { return &X == anA;}
private:
A* anA;
};
