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I have little to no knowledge of C++ and how to use arrays. That being said, what I'm trying to do is create a simple class for chemical elements which automatically decides the number of shells allotted to that element based on just its atomic number. Here's my sample code:

class Element {
   int n, i;
   int s = 1; 

   for (int i = 2; i < n; i += 8) {s += 1;}  

   int shell[s + 1];

   public: Element(int n) {this.n = n;}
};

That snippet of code is supposed to create an array called int shell[s + 1] which contains s-1 shells. I made it s-1 instead of s so I wouldn't constantly confuse myself by referring to shell #1 as shell[0] and so forth. Thus, shell[0] is unused. Or I could do it the other way around and actually use shell[0], but that's irrelevant. As you can see, int s is automatically set to 1 because all elements contain at least one shell. Then there's a for loop that adds shells based on int n. Finally, I declared the array int shell[s + 1].

Ultimately, I got a multitude of errors. Most of them were nonsensical syntax errors, but apparently in C++ you're not allowed to initialize non-final instance variables. That doesn't make much sense to me, because I really need int s to begin at 1 for the for loop. It also tells me that I can't make variable-sized arrays, either. What do?

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1 回答 1

0

您可以std::vector<int>在构造函数中使用和初始化它：

class Element {
   int s, n;
   std::vector<int> shell;

   public: Element(int n) : s(1), n(n) {
       for (int i = 2; i < n; i += 8) {s += 1;}  
       shell.resize(s + 1);
   }
};
于 2013-10-14T08:02:00.020 回答