c++ auto

c++ auto

实际上，写了很长时间的c++，其中c++11中引入的auto是很有用的，但是，之前遇到问auto是否能够保证const和reference(&)的属性时，一时不知道如何回答，所以写一小段程序验证一下结论: auto不能保证掐前面所述的属性, 测试代码如下:

#include 
#include 

using namespace std;

class Test
{
public:
    Test()
    {

    }

public:
    const std::string& getString()
    {
        return str;
    }

public:
    std::string str;
};

int main()
{
    Test test;
    test.str = "abc";
    std::cout << "test.str address = " << (unsigned long long int)(&test.str) << ", value = " << test.str << std::endl;

    auto auto_str = test.getString();
    std::cout << "A auto_str address = " << (unsigned long long int)(&auto_str) << ", value = " << auto_str << std::endl;
    auto_str += "efg";
    std::cout << "B auto_str address = " << (unsigned long long int)(&auto_str) << ", value = " << auto_str << std::endl;

    const std::string& ref_str = test.getString();
    std::cout << "ref_str = " << (unsigned long long int)(&(ref_str)) << ", value = " << ref_str << std::endl;

    return 0;
}

代码运行结果如下:  说明auto仅仅是类型的替代，相关的其他限制，需要自身保证。