Octal to Decimal conversion in JAVA
This tutorial would help in learning the following:
- Conversion of numbers from octal-system (0 to 7) to decimal-system (using 0 to 9)
- Re-conversion of characters into their respective ASCII codes
- Code for Octal to Decimal conversion in JAVA
The decimal number system uses all the 10 digits (0 to 9) to represent a number while the octal number system used eight digits (0 to 7). The following algorithm is used to convert an octal number to a decimal number:
let the octal number be 77
- Give proper index to each digit of the octal number, starting with zero and from the rightmost digit
number->77
index—->10 - multiply the number present at index ‘i’ with the ith power of 8
index 0 -> 7* 80 = 7
index 1 -> 7 * 81 = 56 - add all the products obtained from step 2, to get the equivalent decimal number
7 + 56 = 63
(77)8 ~ (63)10
Each character used in computing is assigned a special ASCII code (decimal-number-system); hence, once an octal code is converted to its equivalent decimal-number code, the latter can be assigned a character as per the ASCII convention.
Note, there can be different encoding systems on different machines.
Code for Octal to Decimal conversion:
//This program follows the convention of giving a fullstop after the code for an individual character public class OctalDeconversion { String octalcode; OctalDeconversion()//default constructor { octalcode="103.157.144.145.40.123.160.145.145.144.171."; } OctalDeconversion(String x)//parameterized constructor { octalcode=x; } public static void main(String args[]) { OctalDeconversion ob; try{//considering the command line argument of the user as the string to be re-converted from octal format ob=new OctalDeconversion(args[0]); }//going with the default string in case of any exceptions with the command line argument catch(Exception e){ob=new OctalDeconversion();}; System.out.print("The decoded value of octal code "+ob.octalcode+" is: "); ob.octalToString(ob.octalcode); } char octal(char array[]) { int code=0; int temporary; int i; int j=0; for(i=0;array[i]!='\0';i++);//obtaining the index of the last code-character in array[] for(--i;i>=0;i--){ temporary = ((int)array[i]) - ((int)('0')); code+=temporary*(int)(Math.pow(8,j++));//Math.pow() helps in giving the required power of 8 } return (char)code;//returning the character corresponding to the integer-code whose value is in 'code' } void octalToString(String code) { char helper[]=new char[10+1];//assuming that the length of octal code for one character will not exceed 10 int index = 0; for(int i=0;i<code.length();i++){ if(code.charAt(i)=='.')//printing the value of the code for one character { helper[index]='\0'; System.out.print(octal(helper)); index=0; } else//stacking up the incomplete code for one character { helper[index++]=code.charAt(i); } } } }//class ends
Output: (without command-line argument)
The decoded value of octal code 103.157.144.145.40.123.160.145.145.144.171. is: Code Speedy
Summary:
char octal(char[]):
- the index of the last character in array[] is stored in ‘i’
- the value of ‘j’ corresponds with the required power of 8 that is required for the character at given index ‘i’
- the numerical value of the character-code at index ‘i’ is stored in ‘temporary’
- the sum of products for different indices is stored in ‘code’
- the character corresponding to the value of ‘code’ is returned
void octalToString(String)
- helper[] stores the octal code for one character at a time
- octal(char[]) is called and helper[] is passed to it to print the corresponding character for the octal code in helper[]
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