链接器找不到C ++静态成员 [英] linker cannot find a C++ static member

问题描述

当我在X代码中写简单的C ++代码时，它显示了链接器错误。

When i write simple C++ code in X-code, it shows Linker Error.

架构x86_64的未定义符号：
Emp :: id ，引用自：
main.o中的Emp :: Emp（）
ld：没有为架构x86_64找到符号
clang：error：linker命令失败，退出代码为1 -v查看调用）

Undefined symbols for architecture x86_64: "Emp::id", referenced from: Emp::Emp() in main.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

#include <iostream>
using namespace std;
class Emp
{

    public:
      static int id;
      int sal;

   Emp()
   {
      Emp::id =10;   // When i comment this line its working fine.
   };
};
int main(int argc, const char * argv[])
{
    Emp Ram;
    cout << Ram.sal ;
    return 0;
 }

推荐答案

$ c> id 作为静态变量。

You have declared id as a static variable. You then set it in every constructor call, which is probably not what you want to do.

对于一个'fix'，你可以在main之上添加以下行：

For a 'fix', you can add the following line above main:

int Emp::id = 0;

但是，您可能不希望它是静态的。有关静态类变量的详细信息，请参见此页

However, you may not want that to be static. For more information on static class variables, see this page

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