Re: [Dev-C++] Question about increment..

On 9/20/2012 9:08 PM, Mani wrote:
> I think I might argue with one point way below.. please scroll down..
>
> On Thu, Sep 20, 2012 at 4:08 PM, Reid Thompson <Rei...@at...> wrote:
>> On Thu, 2012-09-20 at 12:54 -0400, Mani wrote:
>>> Hi,
>>>
>>> I recently to try some toy things in DevC++ (version I am using is 4.9.9.2)
>>>
>>> The code I had was this:
>>>
>>>      int a = 1, b = 2;
>>>      int c = a++ + b++ + a + b;
>>>
>>>      cout << "a = " << a << endl;
>>>      cout << "b = " << b << endl;
>>>      cout << "c = " << c << endl;
>>>
>>> I expected the c value to be 8 (by operator precedence, ++ has higher
>>> precedence than +, so do in order:
>>> a++, then b++
>>> then do (a++ + b++)
>>> then add the previous result and a
>>> then add the previous result and b
>>>
>>> but the answer I got was 6..
>>>
>>> what might be the reason for this..??
>>>
>>> thanks, murali
>>>
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>> [16:06:54][94s] rthompso@raker2> ~
>> $ cat helloworld.c
>> #include <stdio.h>
>> #include <stdlib.h>
>> int main(void)
>> {
>>      int a = 1, b = 2;
>>      int c = a++ + b++ + a + b;
>>
>>      printf("c is %d\n", c);
>>      a = 1;
>>      b = 2;
>>      c = ++a + ++b + a + b;
>>
>>      printf("c is %d\n", c);
>>
>>      return 0;
>>
>> }
>>
>> [16:07:01][0s] rthompso@raker2> ~
>> $ cat Hello.cs
>> using System;
>>
>> class Program
>> {
>>      static void Main()
>>      {
>>          int a = 1, b = 2;
>>          int c = a++ + b++ + a + b;
>>
>>          Console.WriteLine(c);
>>          Console.WriteLine("Hello world!");
>>
>>          a = 1;
>>          b = 2;
>>          c = ++a + ++b + a + b;
>>          Console.WriteLine(c);
>>          Console.WriteLine("Hello world!");
>>
>>
>>          a = 1;
>>          b = 2;
>>          c = a++ + b++;
>>          int d =  c + a + b;
>>
>>          Console.WriteLine(d);
>>      }
>> }
>>
>> [16:07:26][0s] rthompso@raker2> ~
>> $ ./a.out
>> c is 6
>> c is 10
>>
>> [16:07:30][0s] rthompso@raker2> ~
>> $ mono Hello.exe
>> 8
>> Hello world!
>> 10
>> Hello world!
>> 8
>>
>>
>> gcc C
>> n++ -> increment after use
>>>      int a = 1, b = 2;
>>>      int c = a++ + b++ + a + b;
>>            c = 1 + 2 + 1 + 2
>>            c = 6
>>
>> ++n -> increment before use
>>>      int a = 1, b = 2;
>>>      int c = ++a + ++b + a + b;
>>            c = 2 + 3 + 2 + 3
>>            c = 10
>>
>> mcs csharp
>> evidently creates an incremented copy and uses it with the original
>> value
>>>      int a = 1, b = 2;
>>>      int c = a++ + b++ + a + b;
>>            c = 2 + 3 + 1 + 2
>>            c = 8
>>>>> BEGIN: Murali:
> How can you be sure that this is what happens.. I am inclined to
> believe what happens is:
> c = 1 + 2 + 2 + 3
> c = 8
>
>>>>> END: Murali
>> ++n -> increment before use
>>>      int a = 1, b = 2;
>>>      int c = ++a + ++b + a + b;
>>            c = 2 + 3 + 2 + 3
>>            c = 10
>>
>>          a = 1;
>>          b = 2;
>>          c = a++ + b++;
>>          int d =  c + a + b;
>>          c = 5
>>          d = 5 + 1 + 2
>>          d = 8
>>
>>
ok -- you are most likely correct.