C++中向量的通用向量
在 C++ 中是否有一种好方法来实现(或伪造)通用向量向量的类型?
Is there a good way in C++ to implement (or fake) a type for a generic vector of vectors?
忽略向量向量何时是一个好主意的问题(除非有一些等效的东西总是更好).假设它确实准确地对问题建模，而矩阵不能准确地对问题建模.还假设将这些东西作为参数的模板化函数确实需要操作结构(例如调用 push_back)，因此它们不能只采用支持 [][] 的泛型类型.
Ignore the issue of when a vector of vectors is a good idea (unless there's something equivalent which is always better). Assume that it does accurately model the problem, and that a matrix does not accurately model the problem. Assume also that templated functions taking these things as parameters do need to manipulate the structure (e.g. calling push_back), so they can't just take a generic type supporting [][].
我想做的是:
template<typename T>
typedef vector< vector<T> > vecvec;
vecvec<int> intSequences;
vecvec<string> stringSequences;
当然这是不可能的，因为 typedef 不能被模板化.
but of course that's not possible, since typedef can't be templated.
#define vecvec(T) vector< vector<T> >
很接近，并且可以避免在对 vecvecs 进行操作的每个模板化函数中重复类型，但不会受到大多数 C++ 程序员的欢迎.
is close, and would save duplicating the type across every templated function which operates on vecvecs, but would not be popular with most C++ programmers.
推荐答案
您想要模板类型定义.目前的 C++ 尚不支持 .解决方法是做
You want to have template-typedefs. That is not yet supported in the current C++. A workaround is to do
template<typename T>
struct vecvec {
typedef std::vector< std::vector<T> > type;
};
int main() {
vecvec<int>::type intSequences;
vecvec<std::string>::type stringSequences;
}
在下一个 C++(由于 2010 年称为 c++0x、c++1x)中，这将是可能的:
In the next C++ (called c++0x, c++1x due to 2010), this would be possible:
template<typename T>
using vecvec = std::vector< std::vector<T> >;
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