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

[Mani <man...@gm...>]

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
>
>