Introduction to Java: Some beginners need to master the basic algorithm program-Reverse output

"Problem" outputs an integer in reverse order.

"Idea" there are three ways to output a number in reverse order:

1) using the while loop

2) Use for loop

3) Use recursion

Code

Program 1: Using the While loop

ImportJava.util.Scanner;classreversenumberwhile{ Public Static voidMain (String args[]) {intNum=0; intReversenum =0; System.out.println ("Input Your number and press ENTER:"); //This statement would capture the user inputScanner in =NewScanner (system.in); //captured input would is stored in number numnum =In.nextint (); //While Loop:logic to find out the reverse number       while(num! = 0) {Reversenum= Reversenum * 10; Reversenum= Reversenum + num%10; Num= NUM/10; } System.out.println ("Reverse of input number is:" +reversenum); }}

Output Result:

145689986541

Program 2: Using a For loop

ImportJava.util.Scanner;classforloopreversedemo{ Public Static voidMain (String args[]) {intNum=0; intReversenum =0; System.out.println ("Input Your number and press ENTER:"); //This statement would capture the user inputScanner in =NewScanner (system.in); //captured input would is stored in number numnum =In.nextint (); /*For Loop:no initialization part as Num are already * initialized and No increment/decrement part as logic * num = NUM/10 already decrements the value of Num*/       for(; num! = 0; ) {Reversenum= Reversenum * 10; Reversenum= Reversenum + num%10; Num= NUM/10; } System.out.println ("Reverse of specified number is:" +reversenum); }}

Output Result:

5678911111198765

Program 3: Using recursion

ImportJava.util.Scanner;classrecursionreversedemo{//A method for reverse    Public Static voidReversemethod (intNumber ) {       if(Number < 10) {System.out.println (number); return; }       Else{System.out.print ( number% 10); //Method is calling Itself:recursionReversemethod (NUMBER/10); }   }    Public Static voidMain (String args[]) {intNum=0; System.out.println ("Input Your number and press ENTER:"); Scanner in=NewScanner (system.in); Num=In.nextint (); System.out.print ("Reverse of the input number is:");    Reversemethod (num);   System.out.println (); }}

Output Result:

5678901Reverseof the input number is: 1098765

Of course, if the number to be reversed has already been initialized, you don't have to enter it from the keyboard, such as:

class reversenumberdemo{   publicstaticvoid  main (String args[])   {       int num=123456789;//not from keyboard input, directly initialized to an integer value.       int reversenum =0;        while (num! = 0 )      {          = Reversenum * Ten;           = Reversenum + num%10;           = Num/10;      }      System.out.println ("Reverse of specified number is:" +reversenum);}   }

Getting Started with Java: Some beginners need to master the basic algorithmic program-Reverse output