使用“新” c++ 中带有结构的关键字
#include "PQueue.h"
struct arcT;
struct coordT {
double x, y;
};
struct nodeT {
string name;
coordT* coordinates;
PQueue<arcT *> outgoing_arcs;
};
struct arcT {
nodeT* start, end;
int weight;
};
int main(){
nodeT* node = new nodeT; //gives error, there is no constructor
}
我的目的是在堆中创建一个新的nodeT。错误是：
错误 C2512：“nodeT”：没有合适的默认构造函数可用
#include "PQueue.h"
struct arcT;
struct coordT {
double x, y;
};
struct nodeT {
string name;
coordT* coordinates;
PQueue<arcT *> outgoing_arcs;
};
struct arcT {
nodeT* start, end;
int weight;
};
int main(){
nodeT* node = new nodeT; //gives error, there is no constructor
}
My purpose is to create a new nodeT in heap. Error is:
error C2512: 'nodeT' : no appropriate default constructor available
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评论（3）
PQueue没有合适的默认构造函数，因此编译器无法生成nodeT的默认构造函数。为PQueue创建适当的默认构造函数，或者为nodeT添加用户定义的默认构造函数，以适当地构造outgoing_arcs。PQueue<arcT *>does not have an appropriate default constructor, so a default constructor fornodeTcannot be generated by the compiler. Either make an appropriate default constructor forPQueue<arcT *>or add a user-defined default constructor fornodeTwhich constructsoutgoing_arcsappropriately.如果问题中当前发布的代码是精确副本，则导致此错误的唯一可能原因是
PQueue<...>未定义默认构造函数，而是定义了另一个构造函数。否则这段代码会编译。
更准确地说，由于您没有为结构定义构造函数，C++ 会尝试自动生成它们。但它只能做到这一点，只要它的所有成员变量都是适当的默认构造或可初始化的。
std::string有一个默认的构造函数，而coordT*作为一个指针，可以被初始化。因此只有PQueue<...>仍然是罪魁祸首。If the currently posted code in the question is an exact copy, then the only possible cause for this error is that
PQueue<…>doesn’t define a default constructor, and defines another constructor instead.Otherwise this code would compile.
More precisely, since you didn’t define a constructor for your structures, C++ tries to auto-generate them. It can only do this, though, as long as all its member variables are appropriately default constructible or initialisable.
std::stringhas a default constructor, andcoordT*, being a pointer, can be initialised. So onlyPQueue<…>remains as the culprit.这可能不是你的问题，但你在 arcT 的这一行上只声明了一个指针：-
你已经将 start 声明为指针，将 end 声明为实际的 nodeT 对象。这是你想做的吗？
THis may not be your problem but you've only declared one pointer on this line in arcT :-
You've declared start as a pointer and end as an actual nodeT object. Is this what you wanted to do?