CODEWITHSUNDEEP
c++arrayspointers
someGuy
someGuy

Reputation: 77

C++ pointing a pointer to an array and accessing?

how do I access the value of a pointer to an array first element. I have attempted below but code won't build.

int _tmain(int argc, _TCHAR* argv[])
{


/// pointers array

  mint *yellow [5];



/// each pointers array point to an an array of 10 elements
for (int i = 0; i < 5; i++)
{
    yellow[i] = new int [10] ;
}

/// assigning to pointer 1, array 1, element 1 the value of 0;
///
*yellow[0][1][0] = 0;


std::cout << *yellow[0][1][0];


system("pause");
return 0;
}

Update-

although that I don't have an element 20 but I am still able to assign and print the element 20 

  int _tmain(int argc, _TCHAR* argv[])
  {


/// pointers array

int *yellow [5];



/// each pointers array to an an array of 10 elements
for (int i = 0; i < 5; i++)
{
    yellow[i] = new int [10] ;
}

/// assigning to pointer 1, array 1, element 1 the value of 0;
///
yellow[0][20] = 0;


std::cout << yellow[0][20];


system("pause");
return 0;

Upvotes: 0

Views: 52

Answers (2)

Robert Blatner
Robert Blatner

Reputation: 81

Actually, by assigning to yellow[0][20] you are invoking undefined behavior. In other words, your program isn't always gauranteed to print 0, the value stored at yellow[0][20].

Upvotes: 0

R Sahu
R Sahu

Reputation: 206557

To access the first element of the first array, use

yellow[0][0] = 0;

or

 (*yellow)[0] = 0;

To access the third element of the second array, use

yellow[1][2] = 0;

or

 (*(yellow+1))[2] = 0;

To generalize the idea... To access the N-th element of the M-th array, use

yellow[M-1][N-1] = 0;

or

 (*(yellow+M-1))[N-1] = 0;

Upvotes: 1

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