任意一个类型与字符串相加自动转化成字符串

I was doing code review, someone wrote something as the following.

It can totally build and it's the first time I know this.

 

int i = 1;

string s = i+""; //任意一个类型与字符串相加自动转化成字符串。没有直接调用C#类库，隐含间接调用的。