Difference between "0" and "new int()" in C#

Question

Possible Duplicate:
Where and why use int a=new int?

What's the difference between these two below?

int i =0; 
int i = new int();

Is there any difference in case of memory allocation ? Is there any other difference?

Answer 1

Both of them compiles to same thing.

Suppose you have:

static void Main(string[] args)
{
    int i = 0;
    int j = new int();

    Console.Write("{0}{1}", i, j);
}

If you build in Release mode and see the executable in ILSpy, it compiles to:

private static void Main(string[] args)
{
      int i = 0;
      int j = 0;
      Console.Write("{0}{1}", i, j);
}

new int() is same as default(int)

Here is the IL

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // Code size       27 (0x1b)
  .maxstack  3
  .locals init ([0] int32 i,
           [1] int32 j)
  IL_0000:  ldc.i4.0
  IL_0001:  stloc.0
  IL_0002:  ldc.i4.0
  IL_0003:  stloc.1
  IL_0004:  ldstr      "{0}{1}"
  IL_0009:  ldloc.0
  IL_000a:  box        [mscorlib]System.Int32
  IL_000f:  ldloc.1
  IL_0010:  box        [mscorlib]System.Int32
  IL_0015:  call       void [mscorlib]System.Console::Write(string,
                                                            object,
                                                            object)
  IL_001a:  ret
} // end of method Program::Main

Answer 2

The first one

int i = 0;

Initialize a new integer of name i. Then, sets its value to 0

While the second one

int i = new int();

Initializes a new integer of name i to the default value (which is 0). This is also similar to

int i = default(int);

Thanks,
I hope you find this helpful :)