Why is this integer not incrementing twice? [duplicate] - c#-4.0

Question

This question already has answers here:
C# Increment operator (++) question:Why am i getting wrong output?
(5 answers)
Closed 8 years ago.
I am confused by the results of the code below. Why does 'b' retain a seemingly incorrect value when doing these operations?
int a = 0;
int b = 5;
a = b++;
b = b++;
Console.WriteLine("For b = b++; b=" + b.ToString()); // b should be 7 but it's 6
a = 0;
b = 5;
a = b--;
b = b--;
Console.WriteLine("For b = b--; b=" + b.ToString()); // b should be 3 but it's 4
a = 0;
b = 5;
a = b + 1;
b = b + 1;
Console.WriteLine("For b = b++; b=" + b.ToString());
Output
b=6
b=4
b=6
Can anyone explain this behavior in C# and how it's working?

Answer 1

That's indeed the behavior of postfix operators, as detailed here.
For instance, when you write:
b = b++;
The following happens:
The current value of b is saved,
b is incremented,
The saved value of b is produced by the postfix ++ operator,
The value produced by the operator is assigned to b.
Therefore, b will indeed be assigned its original value, and the incremented value is lost.

Answer 2

Because the ++ and -- operators when placed after the value will evaluate to the value itself, and then increment/decrement the value after the evaluation.
So:
int a = 0;
int b = a++;
After running this code, b will equal 0 and a will equal 1.
This is as opposed to using the operators as prefixes:
int a = 0;
int b = ++a;
After running this code, b will equal 1 and a will equal 1.
This is documented behavior and has been around for a long time.

Answer 3

The instruction a=b++ is stored on the stack but not evaluated because it was not used after that.
To get the correct result, make that instruction have a sense fro example change that line:
Console.WriteLine("For b = b++; b=" + b.ToString());
by that one:
Console.WriteLine("For a = b++; a=" + a.ToString());
Console.WriteLine("For b = b++; b=" + b.ToString()); //should give 7

Answer 4

When you use
int a = 0;
int b = 5;
a = b++;
b = b++;
You set a to be 6, and after that you set b to be 6.
When you write b to commandline, it presents 6 because a was never used when incrementing b.
If you want to use a as well, you'd have to make
int a = 1;
int b = 5;
b = b++;
b += a;
Console.WriteLine("For b = a + b++; b=" + b.ToString());
But overall I don't see any use in this kind of incrementation.