Question

Write a program that asks the user to enter a two-digit number, then prints the number with its digits reversed. Do the problem with a second approach that makes use of the division and modulus operators

Answer 1

@phi

Answer 2

One way is read in a string, and print out the string in reverse order

the 2nd way, we first need the algorithm... did you figure it out ?

Answer 3

No not really. I have been trying to look out other places for reference, but I don't understand what they are saying.

Answer 4

public void reverse(int n) {
int result = 0;
int rem;
while (n > 0) {
rem = n % 10;
n = n / 10;
result = result * 10 + rem;
}
}

Answer 5

Will these line of commands get it? I got this from the website: http://www.javawithus.com/programs/reversing-a-number

Answer 6

yes. For only 2 digits you can probably simplify it a bit.

Answer 7

Can you explain how it will work?

Answer 8

With an example?

Answer 9

@phi

Answer 10

it will take me a few minutes.

Answer 11

ok

Answer 12

#include <stdio.h>

int main()
{
int a, b;

while (1)
{
printf("Enter a number (0 to exit): ");
scanf("%2d", &a);
if (a==0) break;
b= (a % 10)*10+(a/10);
printf("original %2d reversed: %2d\n", a,b);
}
}

Answer 13

I am still unsure about why you would want to divide by 10 and then multiply and then add it to the quotient of a/10

Answer 14

I just can't process what the mathematical things represent or mean

Answer 15

the operator % returns the "remainder"

example: 23 % 10 returns 3 (the remainder after dividing by 10)

if you do an *integer divided* i.e. divide integers (not floats), C returns only the whole number. example 23/10 = 2
once we have those 2 digits we want 3*10 + 2 to reverse the 23 to get 32

Answer 16

This makes so much more sense! Thank you soooo.. much!

Answer 17

Another question (sorry) do I need to use the while loop?

Answer 18

not really, but the program will only run once. If you want to test out various cases, it is more convenient to have it loop.

There is one "bug" that you could tweak: enter 10, the program will print 1
it will leave off the leading 0 ... it might look better to type out 01. If you want that, you have to fix it somehow. maybe do a test, and use a different print statement.

Answer 19

I am writing the program now..

So I will have
`int digits;`
`int last_digit;`
`int first_digit;`
`int reverse;`

Answer 20

ok. The program I posted works, so if you run into trouble, you can use it to debug your work. good luck.

Answer 21

It works!