very strange output with allocation

This is a discussion on very strange output with allocation within the C++ Programming forums, part of the General Programming Boards category; hey all, someone just asked me why their program continues to allocate when the exception has been caught. the exception ...

  1. #1
    Madly in anger with you
    Join Date
    Nov 2005
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    very strange output with allocation

    hey all, someone just asked me why their program continues to allocate when the exception has been caught. the exception being a failed allocation. here is the code:

    Code:
    #include <iostream>
      using std::cin; 
      using std::cout;
      using std::endl;
      using std::cerr;
    #include <iomanip>
       using std::setbase;
    #include <new> using std::bad_alloc;
    
    int main() 
    { 
    double *ptr[1000];
    try
    {
        for (int x = 0; x<1000; x++)
       { 
         ptr[x] = new double [5000000];
         cout << "allocated 5000000 doubles in " << x << endl;
        }
      }
    catch (bad_alloc & memoryAllocationException )
    {
    cerr <<"Exception occured: "<< memoryAllocationException.what() << endl;
    }
    return 0;
    }
    now I'm not a C++ programmer, but I just can't explain this output. here is the example output from this program:

    allocated 5000000 doubles in 37
    allocated 5000000 doubles in 38
    allocated 5000000 doubles in 39
    allocated 5000000 doubles in 40
    allocated 5000000 doubles in 41
    Exception occured: bad alloc exception thrown
    allocated 5000000 doubles in 42
    allocated 5000000 doubles in 43
    allocated 5000000 doubles in 44
    allocated 5000000 doubles in 45
    allocated 5000000 doubles in 46
    allocated 5000000 doubles in 47
    allocated 5000000 doubles in 48
    allocated 5000000 doubles in 49
    allocated 5000000 doubles in 50
    why does it continue to allocate memory which technically shouldn't be available? could this be a buffering problem, because of the fact that the exception message is passing through stderr and not stdout (it is getting printed before the messages in stdout are processed/outputted)?

    could anyone here please offer me some insight as to why such output might be occuring?


    thank you in advance.
    Last edited by Bleech; 11-09-2006 at 12:00 AM.

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  2. #2
    Registered User
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    Mar 2006
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    725
    Might be. Try printing the error through std::cout instead to see what happens.
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  3. #3
    Cat without Hat CornedBee's Avatar
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    8,893
    Hmm ... the endl ought to flush cout ...

    Still, see what happens.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  4. #4
    (?<!re)tired Mario F.'s Avatar
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    Out of curiosity, can't this happen if a faulty set_new_handler is defined without a throw?
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  5. #5
    Cat without Hat CornedBee's Avatar
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    No, then it wouldn't ever throw.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  6. #6
    (?<!re)tired Mario F.'s Avatar
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    Hmm... have to go back to my books then.
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

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