注意如下区别！
private string ChangeString(string src)
{
src = "123";
return src;
}
private string ChangeRefString(ref string src)
{
src = "ref123";
return src;
}
string xx = "456";
MessageBox.Show(ChangeString(xx));//123
MessageBox.Show(xx);//456
ChangeRefString(ref xx);
MessageBox.Show(xx);//ref123
标签：src,MessageBox,string,Show,C#,456,xx,引用 From： https://www.cnblogs.com/sinceret/p/17048912.html