Why am I getting a SEGV?

This is a discussion on Why am I getting a SEGV? within the C++ Programming forums, part of the General Programming Boards category; Hi everyone, I'm trying to erase an array of pointers, but I get a segmentation fault.. any ideas what is ...

  1. #1
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    Why am I getting a SEGV?

    Hi everyone,

    I'm trying to erase an array of pointers, but I get a segmentation fault.. any ideas what is happening :\

    Code:
      vector<employee*> arrayEmployees; // PostfixArray of functors that will be processed.
    
    	for (uint32_t k = 0; k < repeat; ++k) {
    		while (in) { 
                     ...
                    }
            ...
    	}
    
    	for (vector<employee*>::iterator i = arrayEmployees.begin(); i != arrayEmployees.end(); ++i) {
    		delete *i;  
    	}
    	return 0;

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    That depends entirely on what the pointers are that you are trying to free. Did they all come from new?

  3. #3
    C++ Witch laserlight's Avatar
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    Let's see the hidden code. Better yet, post the smallest and simplest compilable code that demonstrates the problem.
    C + C++ Compiler: MinGW port of GCC
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  4. #4
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    Oh.. I am using new to create the object and then push them in an array. However I do this in a sepparate function, could that be a problem.

    like this:
    Code:
    	Employee employee = NULL;
    	for (uint32_t i = 0; i < MAX; ++i) {
    			employee = new employee(false, post[i]);
    			arrayEmployees.push_back(employee);
    	}

  5. #5
    and the Hat of Guessing tabstop's Avatar
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    Quote Originally Posted by afflictedd2 View Post
    Oh.. I am using new to create the object and then push them in an array. However I do this in a sepparate function, could that be a problem.

    like this:
    Code:
    	Employee employee = NULL;
    	for (uint32_t i = 0; i < MAX; ++i) {
    			employee = new employee(false, post[i]);
    			arrayEmployees.push_back(employee);
    	}
    Well, I don't see how that compiles. You can try again, with real code, but better still would be to follow Laserlight's suggestion and create a small, compilable, self-contained example that demonstrates your difficulty.

  6. #6
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    I can't post the code for the app though. Where I am working they don't want any code exposed, I'm not sure how much is too much but I don't like to risk it. Most of the time I do if it's an example of my own code, though. Well anyway, I figured out the problem.

    I basically followed this example:
    Code:
    #include <vector>
    using namespace std;
    
    class Object
    {
    };
    
    int main()
    {
        vector<Object*> vpObject;
        Object* pObject;
    
        for (int i=0; i<5; i++) 
        {
            pObject= new Object;
            vpObject.push_back(pObject);
        }
    
        // delete all pointers in the vector
        while (!vpObject.empty())
        {
            // get first 'element'
            pObject = vpObject.front();
            
            // remove it from the list
            vpObject.erase(vpObject.begin());
    
            // delete the pointer
            delete pObject;
        }
    
    return 0;
    }

  7. #7
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by afflictedd2
    I basically followed this example:
    And you couldn't do it this way?
    Code:
    #include <vector>
    
    class Object
    {
    };
    
    int main()
    {
        using namespace std;
    
        vector<Object*> vpObject;
    
        for (int i=0; i<5; i++)
        {
            vpObject.push_back(new Object);
        }
    
        // delete all pointers in the vector
        for (vector<Object*>::iterator iter = vpObject.begin(), end = vpObject.end();
            iter != end; ++iter)
        {
            delete *iter;
        }
    
        return 0;
    }
    Note that the code is not exception safe: if std::bad_alloc is thrown the objects already dynamically created would never be destroyed. On the other hand, the OS would probably do clean up, but this is just a toy program so we can accept that. Also, if you really want destruction to occur in reverse order of construction then we should write:
    Code:
        // delete all pointers in the vector
        for (vector<Object*>::reverse_iterator iter = vpObject.rbegin(), end = vpObject.rend();
            iter != end; ++iter)
        {
            delete *iter;
        }
    C + C++ Compiler: MinGW port of GCC
    Version Control System: Bazaar

    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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