Thread: manual code for converting binary octa hexa and decimal.

//please help me with my project this will be graded tom. so heres the problem .. theres a main menu choosing binary,octa,hexa,and decimal if i choose decimal it will display decimal menu and then i will input the numbers of binary and then it automatically display the converting process for octa hexa and decimal. and if i choose octa .it display the octa menu and i will input the numbers in octa and then it automatically display the converting process for binary hexa and decimal.. and so on.. but in binary if i input 2 it will display invalid .. the same as octa hexa and decimal... in my code the only problem is the converting process. please help me. :/ our instructor said no one will use a converter for our project. we will code it manually ..so for a moment .. this is my code..


import java.util.*;
import java.lang.*;
public class mainmenu {
public static void main (String[]args)
{
Scanner in = new Scanner(System.in);
char B, O, H, D, Q, L, N , Y;
char bin , pk, pick ;
int binary;
int octa =0;
int hexa =0;
int decimal =0;
double ans;


do {
System.out.println("\311\315\315\315\315\315\315\3 15\315\315\315\315\315\315\315\315\315\315\315\315 \315\273");
System.out.println("\272 MAIN MENU \272");
System.out.println("\272\t\t \272");
System.out.println("\272 B]BINARY \272");
System.out.println("\272 O]OCTA \272");
System.out.println("\272 H] HEXA \272");
System.out.println("\272 D]DECIMAL \272");
System.out.println("\272 Q]QUIT \272");
System.out.println("\272\t\t \272");
System.out.println("\310\315\315\315\315\315\315\3 15\315\315\315\315\315\315\315\315\315\315\315\315 \315\274");
System.out.println("Enter your choice? :");
pick = in.next().charAt(0);
pk = Character.toUpperCase(pick);


switch (pk){
case 'B' :
System.out.println("\311\315\315\315\315\315\315\3 15\315\315\315\315\315\315\315\315\315\315\315\315 \315\273");
System.out.println("\272 Binary Menu \272");
System.out.println("\310\315\315\315\315\315\315\3 15\315\315\315\315\315\315\315\315\315\315\315\315 \315\274");
System.out.println("enter binary numbers:");
binary = in.nextInt();
System.out.println("octa :" +octa);

System.out.println("hexa: " +hexa);
System.out.println("decimal :" +decimal);
break;

case 'O' :
System.out.println("enter octa numbers:");
binary = in.nextInt();
System.out.println("octa :" +octa );
System.out.println("hexa: " +hexa);
System.out.println("decimal :" +decimal);
break;

case 'H' :
System.out.println("enter hexa numbers:");
binary = in.nextInt();
System.out.println("octa :" +octa);
System.out.println("hexa: " +hexa);
System.out.println("decimal :" +decimal);
break;

case 'D' :
System.out.println("enter decimal numbers:");
binary = in.nextInt();
System.out.println("octa :" +octa);
System.out.println("hexa: " +hexa);
System.out.println("decimal :" +decimal);
break;

case 'Q' :
System.exit(0);
break;
default:
System.out.println("no choice");
}
System.out.println("Do you want to continue? yes(Y) no(N)");
L = in.next().charAt(0);
switch(Character.toUpperCase(L))
{

case 'N':
System.exit(0);
break;
case 'Y':
System.out.println("");
break;
default:
System.out.println("Invalid Input");
System.exit(0);

}

}while(L != 'N');



}
}

How would you, by hand, convert a value like "0000 0011" to decimal? To hex? What is your algorithm for doing so? One supposes you have been instructed in one of the long-hand ways of doing this...?

Once you have an idea how to do this, write out the algorithm in English pseudo-code as a method that takes a binary value (hint: probably as a String you might read from the right-most position, number by number) and returns a nicely formatted decimal number as a String, suitable for display.

Points for decorating the output string nicely and accepting Java literal conventions.

e.g.:
"0b1111111110110011" -> "65,459"

A similar algorithm can be derived for generating octal and hex values.

e.g:
"0b1111111110110011" -> "0xFFB3"
- > "0177663

i.e., we can determine from the input what sort of number it is, and we should be able to determine (for example) that "0b0102" is illegal input even before trying to convert it. (See any reference on "Java literals" to see what how to format various literals.)

Note that this does away with most of your interface boilerplate. Just accept a string, validate it as some specific base, and then pass it to the right method(s) to get your formatted result Strings.

The devil is in the details regarding limits and error handling. But you need to start from the inside and work out from there.