- A good way to understand this
conversion algorithm is to look at an
example
of
converting the
2's complement binary number 12
(= 00001111) to its
string representation
- The binary number
000011000 represent
the decimal number 12
The decimal number 12 has 2 digits:
1 and 2 How can you get the digits 1 and 2 from 12 ? Answer: The digit 1 can be obtained from 12 by the computation: 12/10 = 1 The digit 2 can be obtained from 12 by the computation: 12%10 = 2Once we obtain the individual digit, we can use the mapping:
ASCII code = 2's complement code + 48
to obtain their ASCII codes 00110001 (= 49) 00110010 (= 50).
The string "12" can then by found by concatenating the ASCII codes !!!
their binary ASCII code:
- I made a simple Java program to
show you the steps to convert the
2's complement integer 00001100
to its string "12":
// File: /home/cs255001/demo/atoi/JavaOutput_3.java // // Converting a binary number between 0 and 99 to a String // public class JavaOutput_3 { public static void main(String[] args) throws Exception { int i; char[] c = new char[2]; // char array of size 1 // (because we only have 1 character) i = 12; // This statement will assign the // 2's compl code 00001100 to variable i // It actually uses 32 bits, but I list // the last 8 bits for brevity. // *** Change to any value between 0 and 99 c[0] = (char) (i/10 + 48); // c[0] is the left most digit in number i c[1] = (char) (i%10 + 48); // c[1] is the right most digit in number i /* --------------------------------------------- Make a string out of the character(s) ---------------------------------------------- */ String s = new String(c); // Make a string using the characters System.out.println(">>> " + s); /* --------------------------------------------- Prove to students that s is a string ---------------------------------------------- */ s = s + " - hello, this is a string !"; System.out.println(">>> " + s); } }Sample output:
cheung@aruba> java JavaOutput_3 >>> 12 >>> 12 - hello, this is a string !
- Example Program:
(Demo above code)
- Prog file: /home/cs255001/demo/atoi/JavaOutput_3.java
How to run the program:
- To compile: javac JavaOutput_3.java
- To run: java JavaOutput_3
- Quiz:
- What will the above program print when i = 102" ???
Answer:
- :2
The reason is similar to the previous quiz; the character in c[0] is the : character because the ASCII code 58 represents :