“count ++”在C＃中返回什么？

Question

Just ran into a bit of code that wasn't doing what I thought it should. Do other people think this should return 1? Is there a good explanation as to why it doesn't??

int count = 0;

count++.ToString(); // Returns 1 no?

I always thought count++ was the same as count = count + 1...

Answer 1

x++ is a post increment operator. It means that the value of x is incremented, but the old (non-incremented) value of x is returned (0 in your case, to which ToString is applied).

To get the behavior you want, use the pre increment operator ++x .

Answer 2

At least four of the answers posted so far are wrong. It is an extremely common error to believe that the ++ operator has the same ill-defined semantics as it does in C. It does not. The semantics of the ++ operator are well-defined, and are quite different from how they have been described by the incorrect answers here. See my answer to the last time this question was asked for details:

What is the difference between i++ and ++i?

Answer 3

x++ is post increment; the current value (0) is used as the result, then the ++ happens.

A bit like:

var tmp = count;
count++;
Consle.WriteLine(tmp);

The pre-increment (++x) would behave as you expected.

Answer 4

(++i).ToString();

完全符合你的期望。

Answer 5

Your original code will always show 0.

Try this:

(++c).ToString();

This will return 1.

From the MSDN site :

The first form is a prefix increment operation. The result of the operation is the value of the operand after it has been incremented.

The second form is a postfix increment operation. The result of the operation is the value of the operand before it has been incremented.

Answer 6

No, ++count return "1". count++.ToString() execute the ToString() method and then increments count, so it returns "0".