Method arguments reference or not

Question

Could someone explaine please i thought it get just passed by ref when i explicite do it with ref?

var user = new User { Name = "MyName" };
ChangeNameToOtherName(user);      // After method call user.name is "OtherName" < confusing
ChangeNameToOtherName(ref user);  // After method call user.name is "OtherName"

var name = "MyName";
ChangeNameToOtherName(name);      // After method call name is "MyName"
ChangeNameToOtherName(ref name);  // After method call name is "OtherName"

Answer 1

The ref keyword allows you to change the reference of the passed parameter, i.e. change the parameter itself directly.

I assume your method body looks something like this:

void ChangeNameToOtherName(User user) {
  user.Name = "Other name";
}

在这里,您将传递对user类型实例的引用.更改此实例上的属性将修改原始实例.如果指定新对象,则在方法外部将不会显示更改:user = new User { Name = "Name" };

字符串在.NET中是不可变的,您无法修改现有实例.您只能为变量分配新实例.但是更改实例变量引用在函数外部是不可见的(除非ref当然通过).

将类实例传递给函数将使用对该实例的引用来调用该函数.您可以更改实例,但不能更改对该实例的引用.