C++ 出现错误“数组绑定不是']'标记之前的整数常量”
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/16449359/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Getting error "array bound is not an integer constant before ']' token"
提问by user1849859
I am trying to implement a stack using an array but I receive an error.
我正在尝试使用数组实现堆栈，但收到错误消息。
class Stack{
private:
int cap;
int elements[this->cap]; // <--- Errors here
int top;
public:
Stack(){
this->cap=5;
this->top=-1;
};
The indicated line has these errors:
指示的行有以下错误：
Multiple markers at this line
- invalid use of 'this' at top level
- array bound is not an integer constant before ']' token
What am I doing wrong?
我究竟做错了什么？
回答by templatetypedef
In C++, the size of an array must be a constant known at compile-time. You'll get an error if that isn't the case.
在 C++ 中，数组的大小必须是编译时已知的常量。如果不是这种情况，您将收到错误消息。
Here, you have
在这里，你有
int elements[this->cap];
Notice that this->capisn't a constant known at compile-time, since it depends on how big capis.
请注意，这this->cap不是编译时已知的常量，因为它取决于有多大cap。
If you want to have a variably-sized array whose size is determined later on, consider using std::vector, which can be resized at runtime.
如果您想要一个大小可变的数组，其大小稍后确定，请考虑使用std::vector，它可以在运行时调整大小。
Hope this helps!
希望这可以帮助！
回答by Mohamad Ali Baydoun
You cannot use thisin the declaration like that.
thisis a constant pointer passed to non-static methods in your class. It does not exist outside of that scope.
你不能this在这样的声明中使用。
this是传递给类中非静态方法的常量指针。它不存在于该范围之外。
Such array declarations need constant values/expressions for the size. You don't want that, you want a dynamicly sized container. The solution is to use a std::vector.
这样的数组声明需要大小的常量值/表达式。你不想要那个，你想要一个动态大小的容器。解决方案是使用std::vector.
回答by andre
Since other have already explained the cause of this issue, here is a possible solution to resolve it. Since it seems you may not know the array size at compile time and the assignment may restrict the use of std::vector<int>consider using a pointer implementation.
由于其他人已经解释了这个问题的原因，这里有一个可能的解决方案来解决它。由于您似乎在编译时可能不知道数组大小，并且赋值可能会限制std::vector<int>考虑使用指针实现的使用。
#include <algorithm>
class Stack{
private:
int cap;
int* elements; // use a pointer
int top;
public:
Stack(){
this->cap=5;
this->top=-1;
elements = new int[this->cap];
}
Stack(const Stack& s)
: cap(s.cap) , top(s.top), elements(NULL)
{
if(cap > 0) {
elements = new int[cap];
}
std::copy(s.elements , s.elements + cap, elements );
}
Stack& operator=(Stack s) {
swap(s, *this);
return *this;
}
~Stack() {delete [] elements;}
friend void swap(Stack& first, Stack& second)
{
using std::swap;
swap(first.top, second.top);
swap(first.cap, second.cap);
swap(first.elements, second.elements);
}
};
回答by vitalis emanuel setiawan
Change
改变
int elements[this->cap];
to
到
int* elements=new int[cap]
