# C++ Code Example: convert decimal to octal number

To convert a number from the decimal system to the octal system in C++ programming language, the following code example can be used.

``````#include <iostream>
using namespace std;

int main() {
int num, remainder, oct = 0, i = 1;

cout << "Please enter a number: ";
cin >> num;

while (num != 0) {
remainder = num % 8;
num = num / 8;
oct = oct + (remainder * i);
i = i * 10;
}

cout << "Octal number : " << oct << endl;

return 0;
}``````

### Output

``````Please enter a number: 44
Octal number : 54``````

### Code Explanation

This code converts a given decimal number to its octal equivalent. Here is a step-by-step explanation:

1. Input: The user is prompted to input a decimal number using the following line of code:
``````cout << "Please enter a number: ";
cin >> num;``````
1. Conversion: The conversion takes place in a `while` loop, which runs until the `num` becomes 0. In each iteration of the loop, the remainder when `num` is divided by 8 is calculated and stored in the `remainder` variable. The value of `num` is then updated to be `num` divided by 8. The value of `oct` is then updated as `oct = oct + (remainder * i)`, where `i` is initially 1 and is multiplied by 10 in each iteration. This effectively adds the new remainder to the right side of the existing value of `oct`.
2. Output: The final value of `oct` is the octal equivalent of the input decimal number. This value is displayed on the console using the following line of code:
``cout << "Octal number : " << oct << endl;``