Java program example illustrating the use of octal integers

Octal integers is a number system for numbers from 0 to 7 based on base 8. The Int data type is taken into account when storing octal numbers.

Here we will discuss how to use the octal number system −

• Convert decimal to octal

• Convert octal to decimal.

Conversion from decimal number system to octal number system

Basic knowledge of conversion

• Convert any decimal number to the corresponding octal number:

• Continue dividing decimal numbers by base 8 of the octal number system until you receive a quotient of 0.

• Remember to record the remainder at each step.

• Finally write the remainder backwards, and the resulting number is the corresponding octal number.

• Let's look at some examples to understand this concept better.

Example 1 - Consider the decimal number 2894 and find its octal equivalent.

Decimal	    Division		Quotient		Remainder

2894	    2894 / 8		461			6
461	    461 / 8		57			5
57	    57 / 8		7			1
7	    7 / 8		0			7

Thus, 7156 is the octal equivalent of the decimal number 2894.

Example 2 - Consider another decimal number 101 and find its octal equivalent.

Decimal	        Division	Quotient		Remainder

101		101 / 8		12				5
12 		12 / 8		1				4
1 	   	1 / 8		0				1 

Thus, 145 is the octal equivalent of the decimal number 101.

Example

Example

The following program uses custom logic to convert a decimal number to its corresponding octal number. Create a method named DectoOctal with 1 parameter in a class named DecimalToOctal1 to demonstrate how the octal number system works. Here, the decimal number 15 is passed as an actual parameter to the created method and custom logic is used to convert it to the corresponding octal number.

//Java Program to illustrate the decimal to octal conversion
//using custom logic
public class DecimalToOctal1 {
   
   //creating a method to convert decimal numbers into octal numbers
   public static String DectoOctal(int dec) {
      int r;
      String octal="";
      
      //declaring and initializing an array octalchr
      char octalchr[]= {'0', '1', '2', '3', '4', '5', '6', '7'};
      
      //logic for conversion
      while(dec>0) {
         r=dec%8;
         octal=octalchr[r]+octal;
         dec=dec/8;
      }
      return octal;
   }
   public static void main(String args[]) {
      
      //Invoking the above method to get the octal number of the below decimal numbers
      System.out.println("Octal equivalent of decimal number 15 is: "+DectoOctal(15));
      System.out.println("Octal equivalent of decimal number 24 is: "+DectoOctal(24));
      System.out.println("Octal equivalent of decimal number 7 is: "+DectoOctal(7));
      System.out.println("Octal equivalent of decimal number 5 is: "+DectoOctal(5));
   }
}

Output

Octal equivalent of decimal number 15 is: 17
Octal equivalent of decimal number 24 is: 30
Octal equivalent of decimal number 7 is: 7
Octal equivalent of decimal number 5 is: 5

Example

Example

The following program uses library functions to convert decimal numbers to corresponding octal numbers. In a class called DecimalToOctal2, four different decimal numbers are converted to their corresponding octal values ​​using the library function Integer.toOctalString().

//Java Program to demonstrate the conversion of decimal number into its equivalent octal number using a library function
public class DecimalToOctal2 {
   public static void main(String args[]) {
      //By the usage of the Integer.toOctalString() library method
      //to convert a decimal value into a corresponding octal number

      System.out.println("Octal equivalent of decimal number 15 is:" +Integer.toOctalString(15));
      System.out.println("Octal equivalent of decimal number 24 is:" +Integer.toOctalString(24));
      System.out.println("Octal equivalent of decimal number 7 is:" +Integer.toOctalString(7));
      System.out.println("Octal equivalent of decimal number 5 is:" +Integer.toOctalString(5));
   }
}

Output

Octal equivalent of decimal number 15 is:17
Octal equivalent of decimal number 24 is:30
Octal equivalent of decimal number 7 is:7
Octal equivalent of decimal number 5 is:5

Conversion from octal number system to decimal number system

Basic knowledge of conversion

• To convert any octal number to its decimal equivalent:

• Multiply each digit in the decimal number by the reduced power of the base 8 of the octal number (up to the 0th power).

• Let's look at some examples to understand this concept better.

Example 1 − Let us consider an octal number 456 and find its decimal equivalent.

456 = (4 * 8^2) + (5 * 8^1) + (6 * 8^0)
   = (4 * 64) + (5 * 8) + (6 * 1)
   = 256 + 40 + 6
   = 302

Thus, 302 is the decimal equivalent of the octal number 456.

Example 2 - Let us consider another octal number 152 and find its decimal equivalent.

152 = (1 * 8^2) + (5 * 8^1) + (2 * 8^0)
   = (1 * 64) + (5 * 8) + (2 * 1)
   = 64 + 40 + 2
   = 106

Therefore, 106 is the decimal equivalent of the octal number 152.

Example

Example

The following program uses custom logic to convert a decimal number to its corresponding octal number. Create a method named OctToDec with 1 parameter in a class named OctalToDecimal1 to demonstrate how the octal number system works. Here, four different octal numbers are passed as actual parameters to the created method and custom logic is used to convert them into corresponding decimal numbers.

//Java Program to illustrate the conversion of Octal to Decimal
//using custom logic
public class OctalToDecimal1 {
   //Declaring a method to perform a conversion
   public static int OctToDec(int oct) {
      //Declaring variable to store a decimal number
      int dec = 0;
      //Declaring variable to use in power
      int p = 0;
      //generating the logic
      while(true) {
         if(oct == 0) {
         break;
         } else {
            int t = oct % 10;
            dec += t * Math.pow(8, p);
            oct = oct / 10;
            p++;
         }
      }
      return dec;
   }
   public static void main(String args[]) {
      //displaying the result of the conversion
      System.out.println("Equivalent Decimal of octal number 673 is: "+OctToDec(673));
      System.out.println(" Equivalent Decimal of octal number 71 is: "+OctToDec(23));
      System.out.println("Equivalent Decimal of octal number 100 is: "+OctToDec(100));
      System.out.println("Equivalent Decimal of octal number 88 is: "+OctToDec(10));
   }
}

Output

Equivalent Decimal of octal number 673 is: 443
Equivalent Decimal of octal number 71 is: 19
Equivalent Decimal of octal number 100 is: 64
Equivalent Decimal of octal number 88 is: 8

Example

Example

The following program uses library functions to convert octal numbers to corresponding decimal numbers. In a class called OctalToDecimal2, four different octal numbers are passed as input to the library method Integer.parseInt() and they are converted into corresponding decimal numbers.

//Java Program to demonstrate the conversion of an octal number into its equivalent decimal number using a library function
public class OctalToDecimal2 {
   public static void main(String args[]) {
      System.out.println("Equivalent Decimal of octal number 673 is " + Integer.parseInt("673",8));
      System.out.println("Equivalent Decimal of octal number 673 is " + Integer.parseInt("23",8));
      System.out.println("Equivalent Decimal of octal number 673 is " + Integer.parseInt("100",8));
      System.out.println("Equivalent Decimal of octal number 673 is " + Integer.parseInt("10",8));
   }
}

Output

Equivalent Decimal of octal number 673 is 443
Equivalent Decimal of octal number 673 is 19
Equivalent Decimal of octal number 673 is 64
Equivalent Decimal of octal number 673 is 8

in conclusion

This article clarifies the usage of octal numbers. Here we discuss the conversion methods between octal and decimal through some examples and java programs.

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