Java Reverse Number
I have given here Java code to reverse a given number. It counts the digits and then it uses / and % operators and simple multiplication to reverse the number.
Source Code
import java.lang.*;
import java.util.*;
import java.io.*;
class ReverseNumber
{
public static String ReadString()
{
try
{
InputStreamReader input = new InputStreamReader(System.in);
BufferedReader reader = new BufferedReader(input);
return reader.readLine();
}
catch (Exception e)
{
e.printStackTrace();
return "";
}
}
public static int ReadInteger()
{
try
{
InputStreamReader input = new InputStreamReader(System.in);
BufferedReader reader = new BufferedReader(input);
return Integer.parseInt(reader.readLine());
}
catch (Exception e)
{
e.printStackTrace();
return 0;
}
}
static int CountNumberOfDigits_UsingLog(int number)
{
return (int)(Math.log((double)number) + 1);
}
static int CountNumberOfDigits(int number)
{
int numdgits = 0;
do
{
number = number / 10;
numdgits++;
} while (number > 0);
return numdgits;
}
public static void main(String[] args)
{
System.out.println("\nProgram to find the reverse of a number. Enter -1 to exit");
while(true)
{
System.out.print("\n\nEnter a Number (-1 to exit): ");
int n = ReadInteger();
if(n < 0)
break;
int number = n;
int index = 0;
int numdigits = CountNumberOfDigits(number);
System.out.format("Number of digits in %d is: %d\n", number, numdigits);
int result = 0;
for (int i = 0; i < numdigits; i++)
{
result *= 10;
result += n % 10;
n = n / 10;
}
System.out.format("The reverse of number %d is: %d\n", number, result);
}
}
}
Output
|
|