我正在尝试使用指向C风格字符串的指针列表中的元素填充字符串向量。
这很有效。
int main()
{
//typedef char cstr[];
using cstr = char[];
std::list<cstr*> lict(10);
std::vector<std::string> vec;
for(auto c:lict)
vec.push_back(*c);
return 0;
}
然而，当我尝试使用lict的范围分配给vec时，我收到了一个巨大的错误信息。
int main()
{
using cstr = char[];
std::list<cstr*> lict(10);
std::vector<std::string> vec(lict.begin(), lict.end());
return 0;
}
为什么我不能使用第二种方法？
错误消息是：
/usr/bin/../lib/c++/v1/memory:1681:31: error: no matching constructor for initialization of
'std::__1::basic_string<char>'
::new((void*)__p) _Up(_VSTD::forward<_Args>(__args)...);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/../lib/c++/v1/memory:1608:18: note: in instantiation of function template specialization
'std::__1::allocator<std::__1::basic_string<char> >::construct<std::__1::basic_string<char>, char (*&)[]>'
requested here
{__a.construct(__p, _VSTD::forward<_Args>(__args)...);}
^
/usr/bin/../lib/c++/v1/memory:1492:14: note: in instantiation of function template specialization
'std::__1::allocator_traits<std::__1::allocator<std::__1::basic_string<char> >
>::__construct<std::__1::basic_string<char>, char (*&)[]>' requested here
{__construct(__has_construct<allocator_type, pointer, _Args...>(),
^
/usr/bin/../lib/c++/v1/vector:933:25: note: in instantiation of function template specialization
'std::__1::allocator_traits<std::__1::allocator<std::__1::basic_string<char> >
>::construct<std::__1::basic_string<char>, char (*&)[]>' requested here
__alloc_traits::construct(__a, _VSTD::__to_raw_pointer(this->__end_), *__first);
^
/usr/bin/../lib/c++/v1/vector:1068:9: note: in instantiation of function template specialization
'std::__1::vector<std::__1::basic_string<char>, std::__1::allocator<std::__1::basic_string<char> >
>::__construct_at_end<std::__1::__list_iterator<char (*)[], void *> >' requested here
__construct_at_end(__first, __last);
^
ex9_14b.cpp:9:29: note: in instantiation of function template specialization
'std::__1::vector<std::__1::basic_string<char>, std::__1::allocator<std::__1::basic_string<char> >
>::vector<std::__1::__list_iterator<char (*)[], void *> >' requested here
std::vector<std::string> vec(lict.begin(),lict.end());
^
/usr/bin/../lib/c++/v1/string:1146:31: note: candidate constructor not viable: cannot convert argument of incomplete
type 'char (*)[]' to 'const_pointer' (aka 'const char *')
_LIBCPP_INLINE_VISIBILITY basic_string(const_pointer __s);
^
/usr/bin/../lib/c++/v1/string:1136:40: note: candidate constructor not viable: cannot convert argument of incomplete
type 'char (*)[]' to 'const allocator_type' (aka 'const std::__1::allocator<char>')
_LIBCPP_INLINE_VISIBILITY explicit basic_string(const allocator_type& __a);
^
/usr/bin/../lib/c++/v1/string:1137:5: note: candidate constructor not viable: cannot convert argument of incomplete type
'char (*)[]' to 'const std::__1::basic_string<char>'
basic_string(const basic_string& __str);
^
/usr/bin/../lib/c++/v1/string:1141:5: note: candidate constructor not viable: cannot convert argument of incomplete type
'char (*)[]' to 'std::__1::basic_string<char>'
basic_string(basic_string&& __str)
^
/usr/bin/../lib/c++/v1/string:1167:5: note: candidate constructor not viable: cannot convert argument of incomplete type
'char (*)[]' to 'initializer_list<value_type>'
basic_string(initializer_list<value_type> __il);
^
/usr/bin/../lib/c++/v1/string:1161:9: note: candidate constructor template not viable: requires 2 arguments, but 1 was
provided
basic_string(_InputIterator __first, _InputIterator __last);
^
/usr/bin/../lib/c++/v1/string:1164:9: note: candidate constructor template not viable: requires 3 arguments, but 1 was
provided
basic_string(_InputIterator __first, _InputIterator __last, const allocator_type& __a);
^
/usr/bin/../lib/c++/v1/string:1134:31: note: candidate constructor not viable: requires 0 arguments, but 1 was provided
_LIBCPP_INLINE_VISIBILITY basic_string()
^
/usr/bin/../lib/c++/v1/string:1138:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
basic_string(const basic_string& __str, const allocator_type& __a);
^
/usr/bin/../lib/c++/v1/string:1144:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
basic_string(basic_string&& __str, const allocator_type& __a);
^
/usr/bin/../lib/c++/v1/string:1148:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
basic_string(const_pointer __s, const allocator_type& __a);
^
/usr/bin/../lib/c++/v1/string:1150:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
basic_string(const_pointer __s, size_type __n);
^
/usr/bin/../lib/c++/v1/string:1152:5: note: candidate constructor not viable: requires 3 arguments, but 1 was provided
basic_string(const_pointer __s, size_type __n, const allocator_type& __a);
^
/usr/bin/../lib/c++/v1/string:1154:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
basic_string(size_type __n, value_type __c);
^
/usr/bin/../lib/c++/v1/string:1156:5: note: candidate constructor not viable: requires 3 arguments, but 1 was provided
basic_string(size_type __n, value_type __c, const allocator_type& __a);
^
/usr/bin/../lib/c++/v1/string:1157:5: note: candidate constructor not viable: requires at least 2 arguments, but 1 was
provided
basic_string(const basic_string& __str, size_type __pos, size_type __n = npos,
^
/usr/bin/../lib/c++/v1/string:1169:5: note: candidate constructor not viable: requires 2 arguments, but 1 was provided
basic_string(initializer_list<value_type> __il, const allocator_type& __a);
答案 0 :(得分：1)
您创建一个包含指向char指针的10个指针的列表，即您列出的元素类型为char**，但您希望它们的类型为char*或{{1} }。请注意，修复类型将导致程序具有不确定的行为：使用char const*调用std::string构造函数的前提条件是指针绑定到有效的C字符串。
答案 1 :(得分：0)
因为行：
std::vector<std::string> vec(lict.begin(), lict.end());
使用具有以下原型的构造函数（请参阅here）：
template< class InputIt >
vector( InputIt first, InputIt last, const Allocator& alloc = Allocator() );
first和last是容器中的迭代器，其包含的类型必须与容器的相同，即std::string。
答案 2 :(得分：0)
候选构造函数不可行：无法将不完整类型'char（*）[]'的参数转换为'const_pointer'（又名'const char *'）
列表的值类型无法转换为std::string。
尝试const char*：
std::list<const char*> lict{"Hello", "World"};
std::vector<std::string> vec(lict.begin(), lict.end());
请参阅here