runtime error

This is a discussion on runtime error within the C Programming forums, part of the General Programming Boards category; Hi everyone, working on a data structers project on dev-c++ as compiler and problem is when compile&run it freezes but ...

  1. #1
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    Exclamation runtime error

    Hi everyone, working on a data structers project on dev-c++ as compiler and problem is when compile&run it freezes but when click debug, (magically) it works. So what do you think I missing

  2. #2
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    Your code is probably doing an invalid operation with a pointer. Anything that reorganises how your program uses memory can affect what happens as a result of an invalid pointer operation (including symptoms seeming to disappear when debugging, but coming back otherwise).
    Right 98% of the time, and don't care about the other 3%.

  3. #3
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    my struct is like that:
    Code:
    struct charDesc
    {
          char ch;
          int freq;
          int index;
    };
    struct charDesc chars[256];
    
    
    struct HeapStruct
    {
          int capacity;
          int size;
          struct charDesc *elements;
    };
    typedef struct HeapStruct *priorityQueue;
    So can't see the Error in this function.
    Code:
    void InsertPriorityQueue(int index,int freq,char ch, PriorityQueue h) {
        int i;
    
    
        if (IsFullPriorityQueue(h)) 
        {
            printf("Priority queue is full!\n");
            return;
        }
        h->size++;
        for (i = h->size; h->elements[i/2].freq > freq; i /= 2)
            {
                 h->elements[i].ch = h->elements[i/2].ch;
                 h->elements[i].freq = h->elements[i/2].freq;
                 h->elements[i].index = h->elements[i/2].index;
            }
        h->elements[i].index = index;
        h->elements[i].freq = freq;
        h->elements[i].ch = ch;
    }
    Last edited by zebani; 12-28-2011 at 10:57 AM.

  4. #4
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    any opinion?

  5. #5
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    You are starting your for loop at i = h->size, which may be out of range (depending on the rest of your code). You may want i = h->size - 1 instead.

  6. #6
    Algorithm Dissector iMalc's Avatar
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    Don't know about your runtime error as there isn't enough info to find that, but I'd certainly change this:
    Quote Originally Posted by zebani View Post
    Code:
                 h->elements[i].ch = h->elements[i/2].ch;
                 h->elements[i].freq = h->elements[i/2].freq;
                 h->elements[i].index = h->elements[i/2].index;
    to just this:
    Code:
                 h->elements[i] = h->elements[i/2];
    Entire structures can be copied with a single assignment statement.
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

    Linus Torvalds: "But it clearly is the only right way. The fact that everybody else does it some other way only means that they are wrong"

  7. #7
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    Thank you for all guys. The thing is code working now without changes. I guess dynamically allocated memory caused this crash so when debugging there was no error. And thanks for hint iMalc, I wasn't sure this way is OK

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