方法一:
std::unique_ptr<char[]> getHello()
{
　　char* str = new char[12];
　　strcpy( str, "HelloWorld\n" );
　　return std::unique_ptr<char[]>(str);
}

std::unique_ptr<char[]> testStr = getHello();

============================================
方法二:
static void stringDeleter( char* str )
{
　　delete[] str;
};

std::shared_ptr<char> getHelloShared()
{
　　char* str = new char[12];
　　strcpy( str, "HelloWorld\n" );
　　return std::shared_ptr<char>( str, stringDeleter );
}

std::shared_ptr<char> testStr2 = getHelloShared();

============================================
方法三:
std::vector<char> getHelloVector()
{
　　std::vector<char> helloVector( 12 );
　　strcpy( helloVector.data(), "HelloWorld\n" );
　　return helloVector;
}

std::vector<char> testStr3 = getHelloVector();

============================================
利用RAII可以確保記憶體會被正確釋放
不過假如要對付字串，最簡潔漂亮又有效率的寫法還是std::string...
std::string getHelloString()
{
　　return "HelloWorld\n";
}

std::string testStr4 = getHelloString();
compiler極有可能使上面這一行省略建構暫時物件，只呼叫一次testStr4的普通建構子
再不然靠著move建構子不會真的完整複製物件
再再不然std::string也還有copy on write...