// var in C# means have compiler determine type from right part of statement. So 'string x = "abc";' and 'var x = "abc";' are exactly the same
public void ClassCreation()
{
// old way
var c3 = new SomeReallyLongClassNameThatIsDescriptive();
c3.Str1 = "111";
c3.Int1 = 1;
c3.Str2 = "222";
c3.Int2 = 2;
c3.Str3 = "333";
c3.Int3 = 3;
Assert.Equal("111", c3.Str1);
// new way
var c4 = new SomeReallyLongClassNameThatIsDescriptive {
Str1 = "111",
Int1 = 1,
Str2 = "222",
Int2 = 2,
Str3 = "333",
Int3 = 3,
};
Assert.Equal("111", c4.Str1);
}
// var in C# means have compiler determine type from right part of statement. So 'string x = "abc";' and 'var x = "abc";' are exactly the same
public void DecomipleExample()
{
// no difference in code generated
SomeReallyLongClassNameThatIsDescriptive c1 = new SomeReallyLongClassNameThatIsDescriptive();
//00007FF860BEBBC0 mov rcx,7FF8602BC8D8h
//00007FF860BEBBCA call CORINFO_HELP_NEWSFAST(07FF8BF6F7240h)
//00007FF860BEBBCF mov qword ptr[rbp + 30h], rax
//00007FF860BEBBD3 mov rcx,qword ptr[rbp + 30h]
//00007FF860BEBBD7 call CLRStub[MethodDescPrestub]@7ff86012a000(07FF86012A000h)
//00007FF860BEBBDC mov rcx,qword ptr[rbp + 30h]
//00007FF860BEBBE0 mov qword ptr[rbp + 40h], rcx
var c2 = new SomeReallyLongClassNameThatIsDescriptive();
//00007FF860BEBBE4 mov rcx,7FF8602BC8D8h
//00007FF860BEBBEE call CORINFO_HELP_NEWSFAST(07FF8BF6F7240h)
//00007FF860BEBBF3 mov qword ptr[rbp + 28h], rax
//00007FF860BEBBF7 mov rcx,qword ptr[rbp + 28h]
//00007FF860BEBBFB call CLRStub[MethodDescPrestub]@7ff86012a000(07FF86012A000h)
//00007FF860BEBC00 mov rax,qword ptr[rbp + 28h]
//00007FF860BEBC04 mov qword ptr[rbp + 38h], rax
// il of code see no difference notice class name in code (compiler replaces at compile time)
//IL_0000: nop
//SomeReallyLongClassNameThatIsDescriptive c1 = new SomeReallyLongClassNameThatIsDescriptive();
//IL_0001: newobj instance void DotNetCoreNullable.SomeReallyLongClassNameThatIsDescriptive::.ctor()
//IL_0006: stloc.0
//var c2 = new SomeReallyLongClassNameThatIsDescriptive();
//IL_0007: newobj instance void DotNetCoreNullable.SomeReallyLongClassNameThatIsDescriptive::.ctor()
//IL_000c: stloc.1
//IL_000d: ret
}
// var in C# means have compiler determine type from right part of statement. So 'string x = "abc";' and 'var x = "abc";' are exactly the same
public void TestWithVar()
{
// can't do this as var variables HAVE have a right assignment for compiler to determine type (uncomment to see)
// so by using var it avoids nulls in one case
//var c2;
var c2 = new SomeReallyLongClassNameThatIsDescriptive();
Assert.NotNull(c2);
// notice type of variable is the correct type
Assert.IsType <SomeReallyLongClassNameThatIsDescriptive>(c2);
}
public void TestWithoutVar()
{
// notice compiler warning below? When Nullable checking enabled get a warning you are doing something dangerous
SomeReallyLongClassNameThatIsDescriptive c1 = null;
// have to assign to null because compiler wont allow you to use an unassigned variable
Assert.Null(c1);
// can't test type here because variable is null (uncomment to see)
//Assert.IsType<SomeReallyLongClassNameThatIsDescriptive>(c1);
c1 = new SomeReallyLongClassNameThatIsDescriptive();
// because you never assigned to Str1 and Int1 both null (you get compiler warnings)
Assert.NotNull(c1);
Assert.IsType <SomeReallyLongClassNameThatIsDescriptive>(c1);
}
