Convert number in binary and print out as matrix (C++) - c++

Question

Before you read ahead or try to help, this question is regarding my homework so the requirements to this question will be very specific.
I am writing a code that takes a user input between 0 and 511 and converts it into a binary number. Then the program will replace all the 1's in the binary number with T and all the 0's in the number as H. Afterwards it will print out the results (the binary number with the H and T replacement) as a 3*3 matrix.
This is the desired output (not what I have but what I want):
Enter a number between 0 and 511: 299
The binary number is: 100101011
The matrix is:
THH
THT
HTT
The problem with my code is that I am unsure of how to replace an array that consists of all integers to have certain parts of the index to be either characters or strings. For sure the part with the binary number conversion works but the replacement of the 0's and 1's of the array is where the trouble is at. I am also unsure of how to print out the matrix result. I assume it goes either of 2 ways: 1. The program creates a new array for the previous array's elements stored and prints out the matrix array instead. 2. There is a way to only print the array 3 lines at a time. The only way I can think of is to somehow cut the for loop short and add a line break after every 3 values. I am aware that there are a few pointable errors in my code but I do not know how to fix them.
Although this is in the C++ language, what I have learned is the C style syntax (no std:: kinds of code or stuff like that because I haven't learned it yet and I will not understand it) So far I have learned basic arrays, loops, and functions.
#include <iostream>
using namespace std;
int main(){
int arr[10];
int input, i;
cout<<"Enter a number between 0 and 511: ";
cin>> input;
for(i = 0; input > 0; i++){
arr[i] = (input % 2);
input = input / 2;
}
cout<<"The binary number is: ";
for(i = i - 1; i >= 0; i--){
cout<<arr[i];
}
string newArr[10] = arr[10]; //the error here states that the array initializer must be an initializer list
for(int i = 0; i < sizeof(arr)/sizeof(arr[10]); i++){
if(arr[i] == 1){
arr[i] = "T"; //the error here mentions that a string/ character cannot be assigned with a integer array
}
else{
arr[i] = "H";
}
}
for(int i = 0; i < sizeof(arr)/sizeof(arr[10]); i++){
cout<<arr[i]<< " ";
}
}

Answer 1

This would be sufficient:
#include <iostream>
using namespace std;
int main()
{
// you never actually checked if the input is valid
// so you may or may not want this loop:
int input;
do
{
cout << "Enter a number between 0 and 511: ";
cin >> input;
} while ((input < 0) || (input > 511));
// space for matrix, new lines and null
// to construct a null terminated string
char buffer[3 * (3 + 1) + 1];
int i = 0;
// since the bits are read from left to right
// I will use a mask instead of bit shifting the input
int bit = 1 << 9;// 2^9 == 512
for (int r = 0; r < 3; r++)// rows
{
for (int c = 0; c < 3; c++)// columns
{
// this could come after the check
// and then bit would start at 256
bit >>= 1;
// perform the check and add the corresponding letter
buffer[i++] = (bit & input) ? 'T' : 'H';
}
// add new lines
buffer[i++] = '\n';
}
// if you don't want the last '\n'
// this could be { buffer[--i] = '\0'; }
buffer[i++] = '\0';
cout << buffer;
}