CODEWITHSUNDEEP
c++pointersmemory-management
userA ng
userA ng

Reputation: 53

c++ program crash when executing the function that allocates memory

To be honest, this is an homework assignment, which is about pointers and dynamic memory allocation. This program simulates the manipulation of file directories. Since it contains several files, so I would just paste a few parts here.The program crashed when I executed the function for the third time. I have looked up some solutions for debugging this kind of program crash, but still can't fix it.

struct fs_node
{
    char* name;
    fs_node* parent_directory;
    fs_node** content;
    int no_of_content;

};


bool loop_for_md (fs_node* current_directory, const char* dir_name)
{
    //current_directory is initialized in the main.cpp
    //find out whether the content contains the same name as dir_name

    if(current_directory->content==NULL)
    {
        return true;
    }
    else
    {
        for(int i = 0; i<= current_directory->no_of_content; i++)

        {
            if(strcmp(current_directory->content[i]->name, dir_name)==0)
                return false;
            else
                continue;
        }
    }
    return true;
}


bool make_dir (fs_node* current_directory, const char* dir_name) 
{
    if(current_directory->content==NULL)
    {
        fs_node** n = new fs_node*[20];
        current_directory->content = n;
        fs_node *x = new fs_node();
        current_directory->content[current_directory->no_of_content]=x;
        x->parent_directory = current_directory;
        x->name = new char[100];
        strcpy(x->name, dir_name);
        current_directory->no_of_content++;

        delete x;
        x=0;


    }
    else if(loop_for_md(current_directory, dir_name))//I expect that this part crashes
    {
        fs_node* x = new fs_node();

        current_directory->content[current_directory->no_of_content]=x;
        x->parent_directory = current_directory;

        x->name = new char[100];
        strcpy(x->name, dir_name);
        current_directory->no_of_content++;
        delete x;
        x=0;
    }
    else return false;


    return true;
}

Upvotes: 0

Views: 97

Answers (1)

molbdnilo
molbdnilo

Reputation: 66371

When you have created a new fs_node and inserted it into the directory tree, you shouldn't delete it - that ends the object's lifetime and you're not allowed to use it after that.

Formally, doing so has "undefined behaviour", which means that anything can happen, including a crash much later in a different piece of code or - much worse - appearing to work as intended.

Upvotes: 4

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