我尝试创建如下所示的字符串拆分模板,但出现错误。
struct splitX
{
enum empties_t { empties_ok, no_empties };
};
template <typename Container>
Container& split(
Container& result,
const typename Container::value_type& s,
typename Container::value_type::value_type delimiter,
splitX::empties_t empties = splitX::empties_ok )
{
result.clear();
std::istringstream ss( s );
while (!ss.eof())
{
typename Container::value_type field;
getline( ss, field, delimiter );
if ((empties == split::no_empties) && field.empty()) continue;
result.push_back( field );
}
return result;
}
当我尝试将它与如下 vector 类一起使用时,由于标题错误而失败:
std::getline(myfile,line);
std::vector<std::string> fields;
split(fields,line,' ');
// Test split function
std::cout << line << std::endl;
for(int i = 0; i < fields.size();i++)
std::cout << fields[i];
最佳答案
好的,Microsoft Visual C++ 2008 不喜欢您的 Container::value_type::value_type
。
你可以使用这个可怕的结构:
template <typename T>
struct vte /*value_type_extractor*/
{
typedef typename T::value_type type;
};
template <typename Container>
Container& split(
Container& result,
const typename Container::value_type& s,
typename vte<typename vte<Container>::type>::type delimiter,
splitX::empties_t empties = splitX::empties_ok )
{
typedef typename Container::value_type string_type;
typedef typename string_type::value_type elem_type;
std::basic_istringstream<elem_type> ss( s );
...
}
或者,您可以使用 STL 样式:
#inlcude <iterator>
template <typename OutputIterator, typename StringType>
OutputIterator split(
OutputIterator out,
const StringType& s,
typename StringType::value_type delimiter,
splitX::empties_t empties = splitX::empties_ok )
{
typedef typename StringType::value_type elem_type;
std::basic_istringstream<elem_type> ss( s );
while (!ss.eof())
{
StringType field;
std::getline( ss, field, delimiter );
if ((empties == splitX::no_empties) && field.empty()) continue;
*out++ = field;
}
return out;
}
//somewhere in code
{
...
split(std::back_inserter(your_container), line, ' ');
}
或者,你可以别装模版大神了,写两个重载函数:
template <typename Container>
Container& split(
Container& result,
const std::string& s,
char delimiter,
splitX::empties_t empties = splitX::empties_ok )
{
std::istringstream ss(s);
...
}
template <typename Container>
Container& split(
Container& result,
const std::wstring& s,
wchar_t delimiter,
splitX::empties_t empties = splitX::empties_ok )
{
std::wistringstream ss(s);
...
}
关于c++ - 错误 C2893 : Failed to specialize function template C++,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10909955/