我可以在 C++ 运行时初始化静态 const 成员吗?

2022-01-18 00:00:00 initialization static constants c++

是否可以在运行时初始化我的类的静态 const 成员?这个变量在我的程序中是一个常量，但我想将它作为命令行参数发送.

Is it possible to initialize a static const member of my class during run-time? This variable is a constant throughout my program but I want to send it as a command-line argument. 

//A.h
class A {
public: 
    static const int T;
};

//in main method
int main(int argc,char** argv)
{
    //how can I do something like 
    A::T = atoi(argv[1]);
}

如果无法做到这一点，我应该使用什么类型的变量?我需要在运行时初始化它并保留常量属性.

If this cannot be done, what is the type of variable I should use? I need to initialize it at run-time as well as preserve the constant property.

推荐答案

很抱歉，我不同意在程序中初始化 static const 符号的评论和答案启动而不是在编译时.

I am sorry to disagree with the comments and answers saying that it is not possible for a static const symbol to be initialized at program startup rather than at compile time.

其实这是可能的，我用过很多次，但我是从配置文件中初始化的.比如:

Actually this IS possible, and I used it many times, BUT I initialize it from a configuration file. Something like:

// GetConfig is a function that fetches values from a configuration file
const int Param1 = GetConfig("Param1");
const int MyClass::Member1 = GetConfig("MyClass.Member1");

如您所见，这些静态常量在编译时不一定是已知的.它们可以从环境中设置，例如配置文件.

As you see, these static consts are not necessarily known at compile time. They can be set from the environment, such as a config file.

另一方面，如果可行的话，从 argv[] 设置它们似乎非常困难，因为当 main() 启动时，静态符号已经初始化.

On the other hand, setting them from argv[], seems very difficult, if ever feasible, because when main() starts, static symbols are already initialized.

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