问题
Just curious.
If you go:
string myString;
Its value is null.
But if you go:
int myInt;
What is the value of this variable in C#?
Thanks
David
回答1:
Firstly, note that this is only applicable for fields, not local variables - those can't be read until they've been assigned, at least within C#. In fact the CLR initializes stack frames to 0 if you have an appropriate flag set - which I believe it is by default. It's rarely observable though - you have to go through some grotty hacks.
The default value of int is 0 - and for any type, it's essentially the value represented by a bit pattern full of zeroes. For a value type this is the equivalent of calling the parameterless constructor, and for a reference type this is null.
Basically the CLR wipes the memory clean with zeroes.
This is also the value given by default(SomeType) for any type.
回答2:
default of int is 0
回答3:
The default value for int is 0.
See here for the full list of default values per type: http://msdn.microsoft.com/en-us/library/83fhsxwc.aspx
回答4:
Here is a table of default values for value types in C#: http://msdn.microsoft.com/en-us/library/83fhsxwc.aspx Reference types default value is usually null.
回答5:
String is a reference type. Int is a value type. Reference types are simply a pointer on the stack directed at the heap, which may or may not contain a value. A value type is just the value on the stack, but it must always be set to something.
回答6:
The value for an unitialized variable of type T is always default(T). For all reference types this is null, and for the value types see the link that @Blorgbeard posted (or write some code to check it).
来源：https://stackoverflow.com/questions/2929257/value-of-unassigned-non-nullable-variable-c