Compiler optimization problem in VS 2008
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Thread: Compiler optimization problem in VS 2008

  1. #1
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    Compiler optimization problem in VS 2008

    Hi all,
    I am developing a win 32 application on Visual studio2008.In realease mode with compiler optimization disabled ,my application working fine.But,in maximize speed(Compiler optimization field in C++)its not working properly,Iam explaining with a code
    Code:
    volatile int iExisist=-1;
    iExisist=SearchEntry(_T("abc"));//Searching an entry  
    if(iExiist!=-1)
    {
    	MessageBox(hWnd, _T("Entry Found"), _T("Success"), MB_OK );
    }
    else
    	MessageBox(hWnd, _T("Entry not Found"), _T("ERROR"), MB_OK |MB_ICONERROR);
    While running the application with Compiler optimization disabled Working Fine.In enabled condition(Compiler optimization(Maximize Speed)))always going to else part eventhough i am giving a correct entry.What may be the reason for this problem.Please help me

  2. #2
    VictorN's Avatar
    VictorN is offline Super Moderator Power Poster
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by manjut19 View Post
    ...In enabled condition(Compiler optimization(Maximize Speed)))always going to else part eventhough i am giving a correct entry.What may be the reason for this problem.Please help me
    Define "correct entry". How did you know it was "correct"?
    What does the SearchEntry function do?
    Victor Nijegorodov

  3. #3
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by VictorN View Post
    Define "correct entry". How did you know it was "correct"?
    What does the SearchEntry function do?

    SearchEntry Function will saech the passing string on a Array of string suppose
    Code:
    TCHAR *p[]={_T("abc"),_T("xyz"))
    SearchEntry function search string abc into this array p.
    "correct entry"means the passing string is there in "p"
    if abc string will find on "p"
    and then function will return a value "0"else"-1".This fuction i debugged in "Optimization disabled "state.I am getting the values correctly and code working fine.Running time also no problem,But In "with optimization" not working properly
    Last edited by manjut19; November 21st, 2013 at 02:30 AM.

  4. #4
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    Re: Compiler optimization problem in VS 2008

    Why is iExisist defined as volatile? It would be useful if you posted the code for SearchEntry().
    All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.

  5. #5
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by manjut19 View Post
    While running the application with Compiler optimization disabled Working Fine.In enabled condition(Compiler optimization(Maximize Speed)))always going to else part eventhough i am giving a correct entry.What may be the reason for this problem.Please help me
    You have a bug in your program. Without seeing all the relevant source code, we cannot help you.
    Cheers, D Drmmr

    Please put [code][/code] tags around your code to preserve indentation and make it more readable.

    As long as man ascribes to himself what is merely a posibility, he will not work for the attainment of it. - P. D. Ouspensky

  6. #6
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by manjut19 View Post
    Code:
    volatile int iExisist=-1;
    iExisist=SearchEntry(_T("abc"));//Searching an entry  
    if(iExiist!=-1)
    ...
    Here is your problem: you are setting variable iExisist, while checking iExiist
    Vlad - MS MVP [2007 - 2012] - www.FeinSoftware.com
    Convenience and productivity tools for Microsoft Visual Studio:
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  7. #7
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    Re: Compiler optimization problem in VS 2008

    I suspect this is a typing mistake when the code was entered into the post as the OP says that the code 'works' when not optimised as a misspelt variable would generate a compiler error.
    All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.

  8. #8
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by manjut19 View Post
    SearchEntry Function will saech the passing string on a Array of string suppose
    Code:
    TCHAR *p[]={_T("abc"),_T("xyz"))
    SearchEntry function search string abc into this array p.
    "correct entry"means the passing string is there in "p"
    if abc string will find on "p"
    and then function will return a value "0"else"-1".This fuction i debugged in "Optimization disabled "state.I am getting the values correctly and code working fine.Running time also no problem,But In "with optimization" not working properly
    So you're saying that one of the most used compilers in the world, used by thousands of programmers every day, cannot produce a proper working program from such simple code? You know that can't be the issue -- the problem is definitely your programming.

    First, you need to show your SearchEntry function. I will make a bet -- I bet that you are not searching the array correctly.

    The reason why I think this is that you have an array of string literals. Are you comparing your string literals using == to determine if the string is in the array? If you are, then your function is wrong. You don't compare C-style strings using ==.
    Code:
    int SearchEntry(TCHAR *pStr)
    {
         TCHAR *p[]={_T("abc"),_T("xyz"));
         for (int i = 0; i < 2; ++i )
         {
             if ( pStr == p[i] ) // Wrong!!!
                 return i;
         }
         return -1;
    }
    If your function looks anything like that (using a while loop, do-while, whatever), and you're using == to compare, then that is wrong.

    Again, show your SearchEntry function.

    Regards,

    Paul McKenzie
    Last edited by Paul McKenzie; November 21st, 2013 at 04:58 PM.

  9. #9
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    Re: Compiler optimization problem in VS 2008

    My problem got solved.that is because of,I was using a string copying function in Search function.I was using wcscpy()instead of wcscpy_s().Thanks for all for your valuable reply

  10. #10
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by 2kaud View Post
    I suspect this is a typing mistake when the code was entered into the post as the OP says that the code 'works' ...
    I figured that
    But, since we didn't have the real code, I made an observation on what we did see.
    Vlad - MS MVP [2007 - 2012] - www.FeinSoftware.com
    Convenience and productivity tools for Microsoft Visual Studio:
    FeinViewer - an integrated GDI objects viewer for Visual C++ Debugger, and more...

  11. #11
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by manjut19 View Post
    My problem got solved.that is because of,I was using a string copying function in Search function.I was using wcscpy()instead of wcscpy_s().
    Curiouser and curiouser! Why do you need to make a copy in the search function? Could you please post the *real* code?
    Vlad - MS MVP [2007 - 2012] - www.FeinSoftware.com
    Convenience and productivity tools for Microsoft Visual Studio:
    FeinViewer - an integrated GDI objects viewer for Visual C++ Debugger, and more...

  12. #12
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    Re: Compiler optimization problem in VS 2008

    Quote Originally Posted by manjut19 View Post
    My problem got solved.that is because of,I was using a string copying function in Search function.I was using wcscpy()instead of wcscpy_s().Thanks for all for your valuable reply
    But as Vladimir stated, why do you need to do any copying?

    You stated that you had a static array, and you want to see if a string is an entry in the array. So explain why you need to do any copying.

    From what you described, all you need to do is this:
    Code:
    int SearchEntry(TCHAR *pStr)
    {
         TCHAR *p[]={_T("abc"),_T("xyz"));
         for (int i = 0; i < 2; ++i )
         {
             if ( _tcscmp(pStr,p[i]) == 0 ) 
                 return i;
         }
         return -1;
    }
    Also, why are you using wcscpy_s() for TCHAR strings? You're supposed to be using the TCHAR routines for TCHAR strings, not specific wide or MBCS functions.

    Regards,

    Paul McKenzie

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