Tasks and Solutions: Pointers C ++

40 thoughts on “Tasks and Solutions: Pointers C ++”

1. I do not understand the decision of the first task
   Either I have read and watched bad vidos, or I just forgot something, but as I understand, the pointer – a pointer to a pointer, верно?
   I.e, one line of code, we create two pointers, one of which points to another pointer, which in turn points to the 2.
   Listen as nonsense
   I have a lot of questions,
   As the pointer points to a deuce? Or there is also a variable is created?
   why first, there is need to put * and then there?
   *(*(p = new double*) = new double) = 2;
   And what's going on in this line, I did not understand
   Who understands this help please, I do not understand

   Reply

   1. P pointer is assigned an address dynamically allocated memory that stores a pointer to a double, Next we razadresuem p and obtain a pointer to type double, and dynamically allocates memory to him, razadresatsiey obtain the value of the memory cell (с double) and assign it a value 2.Can be written differently:
      p = new double*;
      *p=new double;
      **p=2;

      Reply

      1. Thank you, in principle I like this and thought, only in my head, it seemed much more difficult

2. By 4 you can tell the task why this error occurs
   “caused the breakpoint to fire”
   not every time .

   Reply

3. Read the lessons and watched the video up to this point, I'm trying to understand with a squeak:
   по 2 task, //double* pArrForFill = 0;// how we made a pointer to an array in this way? like the address of the first cell?
   And, why is that:
   //double* giveMemoryToArr(double* ptrArr, int sizeOfArr)
   {
   ptrArr = new double[sizeOfArr];//
   not like this?
   //double* giveMemoryToArr(double* ptrArr, int sizeOfArr)
   {
   double* ptrArr = new double[sizeOfArr];//

   Reply

   1. double* pArrForFill = 0
      we create a pointer but it is just empty
      //double* giveMemoryToArr(double* ptrArr, int sizeOfArr)
      {
      double* ptrArr = new double[sizeOfArr];//
      this way we re-create the pointer and why do we need to do this when we already have it and we pass it to the function?

      Reply

4. 3 a task:
   #include

   using namespace std;
   void fillArr(int* parr);

   int main()
   {
   setlocale(LC_ALL, “rus”);

   int arr[12]{};
   cout << "Массив до функции:\n";
   cout << "___________________________\n";
   for (int i = 0; i < 12; i )
   {
   arr[i] = i + 1;
   cout << arr[i] <<"|";
   }
   fillArr(arr);
   cout << "\n___________________________\n";
   cout << "\nМассив после функции: \n";
   cout << "___________________________\n";
   for (int i = 0; i < 12; i )
   {
   cout << arr[i] << "|";
   }
   cout << "\n___________________________\n";
   return 0;
   }
   void fillArr(int* parr)
   {

   for (int i = 1; i < 12; i = 2)
   {
   int j = parr[i – 1];
   parr[i – 1] = parr[i];
   parr[i] = j;
   }
   }

   Reply

5. Problem No. 3
   #include
   using namespace std;

   void FillArray(int* arr, int size)
   {
   for (int i = 0; i < size; i )
   {
   arr[i] = rand() % 100;
   }
   }

   void OutputArray(int* arr, int size)
   {
   for (int i = 0; i < size; i )
   {

   cout << i+1 << ": " << arr[i] << "\t";
   }
   cout << endl;
   }

   int main()
   {
   int size = 12;
   int* arr = new int[size];
   FillArray(arr, size);
   OutputArray(arr, size);
   for (int i = 0; i < size; i )
   {
   if ((i+1) % 2 == 0)
   {
   arr[i] = arr[i] + arr[i – 1];
   arr[i – 1] = arr[i] – arr[i – 1];
   arr[i] = arr [i] – arr[i – 1];
   }
   }
   OutputArray(arr, size);
   return 0;
   }

   Reply

6. task №3
   I see a solution like this, simpler as it seems to me
   void fuu(int* pmas)
   {
   for (int i = 0; i < 12; i )
   {
   pmas[i] = i + 1;
   cout << " | " << pmas[i];
   }
   cout << "\n\n============================================\n\n";
   for (int ix = 0; ix 0)
   pmas[ix] = pmas[ix] + 1;
   else
   pmas[ix] = pmas[ix] – 1;
   }

   }
   void main()
   {
   setlocale(LC_ALL, “rus”);
   int * mas = new int[12];
   fuu(but);
   for (int i = 0; i < 12; i )
   {
   cout << " | " << but[i];
   }
   }

   Reply

7. Wouldn't it be easier to decide 3 tasks so?:
   //librayes
   #include
   //std
   using namespace std;

   void swapOddAndShow(int* &p, int size) {
   for (int i = 0; i < size; i ) {
   if (p[i] % 2 == 0) {
   p[i – 1] = p[i];
   p[i] = p[i – 1] – 1;
   }
   }
   for (int i = 0; i < size; i ) { //void swapOddAndShow
   cout << p[i] << endl;
   }

   }

   int main()
   {
   const int size = 12;
   void swapOddAndShow[size];
   for (int i = 0; i < size; i ) { //void swapOddAndShow
   pArr[i] = i + 1;
   cout << pArr[i] << endl;
   }

   cout << "=======================" << endl;

   void swapOddAndShow(pArr, size);

   delete[] pArr;
   }
   void swapOddAndShow, void swapOddAndShow.

   Reply

8. crayon-6237e54a7c45b171657637/ “Frequency Dictionary of Words “

   Reply