我们可以在C ++中重载main()函数吗? [英] Can we overload main() function in C++?

问题描述

由于C ++++允许函数重载，所以我们可以重载main()吗?

Since C+++ allows function overloading, can we overload main()?

例如，

int main(const std::string &)
{
   return 0;
}
int main(int argc, char *argv[])
{
  return main("calling overloaded main");
}

gcc-4.3.4不会编译它，并产生以下错误:(请参见 ideone )

gcc-4.3.4 doesn't compile this, and gives these errors: (see at ideone)

prog.cpp:4:错误:"int main(const std :: string&)"的第一个参数应为"int"
prog.cpp:4:错误:"int main(const std :: string&)"仅接受零个或两个参数
prog.cpp:在功能‘int main(int，char **)’中:
prog.cpp:8:错误:C函数"int main(int，char **)"的声明与
相冲突 prog.cpp:4:错误:此处先前的声明"int main(const std :: string&)"
prog.cpp:在功能‘int main(int，char **)’中:
prog.cpp:10:错误:从'const char *'到'int'的无效转换
prog.cpp:8:错误:函数'int main(int，char **)'的参数太少了
prog.cpp:10:错误:文件

prog.cpp:4: error: first argument of ‘int main(const std::string&)’ should be ‘int’
prog.cpp:4: error: ‘int main(const std::string&)’ takes only zero or two arguments
prog.cpp: In function ‘int main(int, char**)’:
prog.cpp:8: error: declaration of C function ‘int main(int, char**)’ conflicts with
prog.cpp:4: error: previous declaration ‘int main(const std::string&)’ here
prog.cpp: In function ‘int main(int, char**)’:
prog.cpp:10: error: invalid conversion from ‘const char*’ to ‘int’
prog.cpp:8: error: too few arguments to function ‘int main(int, char**)’
prog.cpp:10: error: at this point in file

所以我想知道C ++标准是否明确地禁止main的重载?如果是，那是哪条语句?

So I'm wondering if the C++ Standard explicitly forbids overloading of main? If so, which statement?

推荐答案

是的，它明确禁止这样做.请参阅3.6.1p2

Yes it explicitly forbids that. Refer to 3.6.1p2

实现不应预定义主要功能.此功能不得重载.

An implementation shall not predefine the main function. This function shall not be overloaded.

---

这样，主函数的名称可以保持不变.也就是说，运行时库可以调用具有固定名称(例如main或_main)的符号来跳转到主函数.库的代码将不必依赖于程序的main函数具有的参数列表.

---

This way, the main function's name can stay unmangled. That is, the runtime library can call a symbol having a fixed name (e.g main or _main) to jump to the main function. The libraries' code will not need to depend on what parameter list the program's main function has.

还允许实现为main函数定义其他有效的参数列表(例如，POSIX规范为环境变量指定char **env参数). main的重载是非主函数"还是主函数"(即入口点)，尚不清楚.据推测，如果您声明多个入口点，您将希望得到一个错误，因此此类问题很重要.

The implementation is also allowed to define additional valid parameter lists for the main function (The POSIX spec specifies a char **env parameter for the environment variables, for example). It would not be clear when an overload of main is a "non-main function" or whether it's a "main function", thus an entry point. Presumably, you would want to get an error if you would declare more than one entry point, so such issues are important.

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