Problem to understand a program output

To understand the output you need to know 3 things:

1. The range of an int is from -2,147,483,648 to +2,147,483,647

2. The range of a uint is from 0 to 4,294,967,295.

3. By default, integer operations are unchecked in C#. So there's no runtime exeception if an operation overflows the range of an integer type - values just 'wrap around' instead.

So, in this line:

   Console.WriteLine("{0},{1},{2}", x, x * 2, x << 1);

x starts off at 1024 * 1024 * 1024 = 1,073,741,824 which is within the range of an int and so that's what gets printed out.

x * 2 = 2,147,483,648 

which is one more that the positive limit and so it wraps around to the negative limit of -2,147,483,648.

x << 1 shifts the bits of x one place to the left effectively multiplying it by 2. So the value printed out is exactly the same as x * 2.

Moving onto this line:

   Console.WriteLine("{0},{1},{2}", p, p * 2, p << 1);

p starts off at 1024 * 1024 * 1024 = 1,073,741,824 which is within the range of an uint and so that's what gets printed out.

p * 2 = 2,147,483,648 

is still within the range of a uint and so that's what gets printed out.

p << 1 shifts the bits of p one place to the left effectively multiplying it by 2. So the value printed out is exactly the same as p * 2.

Looking now at:

Console.WriteLine("{0},{1},{2}", x, x * 4, x << 2);

x starts off at 1024 * 1024 * 1024 = 1,073,741,824 which is within the range of an int and so that's what gets printed out.

x * 4 = 4,294,967,296

which is 2,147,483,649 more that the positive limit and so it wraps around to zero ( = -2,147,483,648 + 2,147,483,649 - 1).

x << 2 shift the bits of x two places to the left effectively multiplying it by 4. So the value printed out is exactly the same as x * 4.

Now you know what happens with these, see if you can figure out the other two.