Given a decimal number N, convert N into an equivalent octal number i.e convert the number with base value 10 to base value 8. The decimal number system uses 10 digits from 0-9 and the octal number system uses 8 digits from 0-7 to represent any numeric value.
Illustration:
Input : 33 Output: 41
Input : 10 Output: 12
Approach 1:
- Store the remainder when the number is divided by 8 in an array.
- Divide the number by 8 now
- Repeat the above two steps until the number is not equal to 0.
- Print the array in reverse order now.
Example of converting the decimal number 33 to an equivalent octal number.
Example:
Java
// Java program to convert a Decimal Number to Octal Number// Importing input output classesimport java.io.*;// Main classclass GFG { // Method // To convert decimal to octal static void decToOctal(int n) { // Creating an Integer array of // array to store octal number int[] octalNum = new int[100]; // counter for octal number array int i = 0; while (n != 0) { // Storing remainder in octal array octalNum[i] = n % 8; n = n / 8; i++; } // Printing octal number array in reverse order for (int j = i - 1; j >= 0; j--) System.out.print(octalNum[j]); } // Method 2 // Main driver method public static void main(String[] args) { // Custom input Integer number int n = 33; // Calling the above method to convert // Decimal to Octal number decToOctal(n); }} |
Output
41
Time Complexity: O(log N)
Auxiliary Space: O(1) It is using constant space for variable and array OctalNum
Approach 2:
- Initialize ocatalNum with 0 and countVal with 1 and the decimal number as n
- Calculate the remainder when decimal number divided by 8
- Update octal number with octalNum + (remainder * countval)
- Increment the countval by countval*10
- Divide the decimal number by 8
- Repeat from step 2 until the decimal number is zero
Example:
Java
// Java Program to Convert Decimal Number to Octal Number// Importing input output classesimport java.io.*;// Main classclass GFG { // Method 1 // To calculate the octal value of the given // decimal number static void decimaltooctal(int deciNum) { // Initially declaring and initializing the // octal number with zero int octalNum = 0, countval = 1; int dNo = deciNum; // Condition check while (deciNum != 0) { // Decimals remainder is calculated int remainder = deciNum % 8; // Storing the octalvalue octalNum += remainder * countval; // Storing exponential value countval = countval * 10; deciNum /= 8; } // Print and display the octal number System.out.println(octalNum); } // Method 2 // Main driver method public static void main(String[] args) { // Custom input decimal number int n = 33; // Calling the Method1 to convert above number // to Octal number system decimaltooctal(n); }} |
Output
41
Time Complexity: O(log N)
Auxiliary Space: O(1)
