How to create and store string data in multidimensional array? - c++

Question

How can I create and store string data in a multidimensional array using pointers? My attempt is:
// I declaring row 3 and column 2
string** arr = new string*[3][2]; // I am having issue in here
// I am trying to add data
arr[0] = {"first", "second"};

Answer 1

If you want to be able to initialize a whole sub-array like that with {"first", "second"}, you most likely would need to use a std::vector or std::array instead of manually allocating the memory for the array. Unless you have very specific reasons for using pointers, here is how it could look with vectors:
using str_vec = std::vector<std::string>;
std::vector<str_vec> v(3, str_vec(2, ""));
v[0] = {"first", "second"};
But if you really need pointers, then you'll have to first allocate the memory for the "row" and then do separate allocations for each "column":
std::string** a = new std::string*[3];
for(int i = 0; i < 3; ++i) {
a[i] = new std::string[2];
}
After which you can fill the values one by one:
a[0][0] = "first";
a[0][1] = "second";
And don't forget about deleting all these arrays after you are done. In the reverse order, you first need to delete all columns and then the "row":
for(int i = 0; i < 3; ++i) {
delete[] a[i];
}
delete[] a;

Answer 2

There is mistake in the first line of initialization.
Initialize it like this if you want to avoid any error.
string** arr = new string*[3];
/* It will have count of rows of string you will have like in this statement 3 rows of string. */
// Now you will have to tell about columns for each row separately.
for(int i = 0; i < 3; i++) {
arr[i] = new string[2]; // Here you are initializing each row has 2 columns
}
// Now write your code below...

Answer 3

you can rewrite yours code as following :
string **arr = new string*[3]; // row 3
for(unsigned i = 0; i < 3; i++)
arr[i] = new string[2](); // column 2
arr[0][0] = "first"; arr[0][1] = "second";
for(unsigned i = 0; i < 3; i++){. // yours ans
for(unsigned j = 0; j < 2; j++)
cout << arr[i][j] << " ";
cout << '\n';
}