Post-increment within a self-assignment

Question

I understand the differences between i++ and ++i, but I\'m not quite sure why I\'m getting the results below:

static void Main(string[] args)
{
    int c = 4         


        

Answer 1

The docs say for postfix state:

The result of the operation is the value of the operand before it has been incremented.

This means that when you do:

c = c++;

You're actually re-assigning 42 to c, and that's why you're seeing the console print 42. But if you do:

static void Main(string[] args)
{
    int c = 42;
    c++;
    Console.WriteLine(c);  
}

You'll see it output 43.

If you look at what the compiler generates (in Debug mode), you'll see:

private static void Main(string[] args)
{
    int num = 42;
    int num2 = num;
    num = num2 + 1;
    num = num2;
    Console.WriteLine(num);
}

Which shows the overwrite more clearly. If you look at Release mode, you'll see the compiler optimize the entire call to:

private static void Main(string[] args)
{
    Console.WriteLine(42);
}