strange behavior of integers

Question

I have the following code

 int a = 1, n = 1;

Convert.ToInt32(a = a++ + n--);

Console.WriteLine("a: " + a + " n : " + n);

//If you debug the second line of the code in quick watch the answer is 3.

The answer to above code should be 2, so it is. But if i debug it and see the value in quickwatch the value of a is printed 3. Any idea why the same code results two different values.

@Partha debug it and see the value in quick watch, then its 3 — Muneeb Zulfiqar, Sep 03 '14 at 05:11
what my observation is, The breakpoint on a line gets hit before the code on that line is executed. You should hit F10 on the keyboard to execute the code line and then you will see that the variable contains the expected value. — Muneeb Zulfiqar, Sep 03 '14 at 05:12
I think @MuneebZulfiqar is right about this. When the line is _highlighted_ while debugging, you need to hit F10 to go _past_ that line so its code gets executed. — jay_t55, Sep 03 '14 at 05:16
Related: http://stackoverflow.com/questions/3831341/why-does-this-go-into-an-infinite-loop — zneak, Sep 03 '14 at 05:19
btw: the only *morale* you should really take a way from this is **mutation is evil** ;) — Random Dev, Sep 03 '14 at 05:23

score 0 · Accepted Answer · answered Sep 03 '14 at 05:26

Also note that the increment/decrement operators tailing the variables will be executed after the variable is used in the calculation (but before the result is written into a).

This will be interpreted as a= 1 +1, not a = 2 + 0

Specifcally the programm flows:

Take 1 out of 'a' into calculation memory.

Increment 'a' by 1

take 1 out of 'n' into calculation memory

Decrement 'n' by 1

Set 'a' to the sum of the two values you extracted earlier (not the current values of those variables) Often putting seperate steps into seperate lines can yield a lot better debugging. i.e.:

strange behavior of integers

1 Answers1