Thread: Arrays of pointers...

Originally Posted by tabstop

arrayofPointers was char**, n'est ce pas? I don't feel like going back up to find your code.

Yes, it is.

The following does what I expect:

Code:

#include <iostream>
#include <cstring>

int main() {
    char **arrayofPointers;
    arrayofPointers = new char*[10];
    for (int i = 0; i < 10; ++i) {
        arrayofPointers[i] = new char[15];
        strcpy(arrayofPointers[i], "Hello world!");
    }
    for (int i = 0; i < 10; ++i) {
        std::cout << arrayofPointers[i] << std::endl;
    }
    return 0;
}

I'll leave it to you to compare and contrast. (We'll ignore the lack of delete[]s for the moment.)

Do I really have to point every individual element of the array of pointers to a "new" allocation in dynamic memory? I thought the "arrayOfPointers = new char*[10]" part takes care of all elements. And anyway, seeing as I'm assigning (i.e. pointing) each element of the pointer of arrays to an already existing string, I would think I wouldn't have to do that.

Code:

#include <iostream>
#include <string>

using namespace std;

struct stringStruct {
    stringStruct() : arrayOfPointers(NULL) { initialize(); }
    void initialize();
    string* str;
    string* anotherStr;
    const char** arrayOfPointers;
};

void stringStruct::initialize() {
    str = NULL;
    anotherStr = NULL;
}

void doStuff();

int main() {
  doStuff();
  cin.get();
  return 0;

}

void doStuff() {
  stringStruct object;
  object.str = new string;
  *object.str = "Yes, a string...\n";
  *object.str += "Yes, another string...\n";
  *object.str += "Yes, even another string...\n";
  int sizeOfStr = object.str->size();
  object.anotherStr = new string;
  int sizeOfArrayOfPointers = 0;
  for (int i = 0; i < sizeOfStr; i++) {
      char currentChar = object.str->at(i);
      if (currentChar != '\n') {
          sizeOfArrayOfPointers++; //increment this
      }
  }
  object.arrayOfPointers = new const char*[sizeOfArrayOfPointers];
  int i2 = 0;
  for (int i = 0; i < sizeOfStr; i++) {
    while (object.str->at(i2) != '\n') {
      object.anotherStr += object.str->at(i2);
      i2++;
    }
    object.arrayOfPointers[i] = object.anotherStr->data();
    object.anotherStr = NULL; //reset this pointer
  }
  int sizeOfArray = sizeof(object.arrayOfPointers);
  for (int i = 0; i < sizeOfArray; i++) {
    cout<< object.arrayOfPointers[i] <<endl;
  }

  delete object.str;
  delete [] object.arrayOfPointers;
  delete object.anotherStr;
}