how to display a number's reversal

[nicz888]

if i have 71, i need to display it like 17. backward
if i have 113 i need to display it like 311. first number and last number are swiched

i know i need to used a swap function but how do i used it? how do i extract each digits? thanks

[zandiago]

Good day...welcome aboard. We don't give away codes...you show some effort for us to help you...here's a jumpstart..pretty much we use the integer division and modulus operations ( / and % ). Its a rather simple assignment.:

#include <iostream>//you first need these headers
#include <iomanip>
#include <cmath>
#include <fstream>
#include <string>

using namespace std;

int main()//need your main function
{
int number;//declare a few variables you'll need
int reverse;

cout<<"Please enter a number to get it's reverse"<<endl;//ask the user to enter a number
cin>>number;//user input a number

{
	reverse =(123' ' x)*x+(123' 'x)/1x+(123)' 'x;//if i wanted the reverse of 123 do certain calculation

}
cout<<"The reverse of the number is"<<reverse<<endl;//prints out the reverse of the digits

	return 0;
}

You need to go figure what x is...you'll also need to figure out which operator(division or modulus) goes where i have the ' '
Hope this helps...no more spoon-feeding for you...

[pureinsanity82]

use modulo 10

[zandiago]

Actually, the above may not work.....sorry about that..here's a simple algorithim...not sure why your professor wants you to use switch statements..

First, look at the following for 4754:

(Iteration 1)
0 * 10 + 4 = 4

(Iteration 2)
4 * 10 + 5 = 45

(Iteration 3)
45 * 10 + 7 = 457

(Iteration 4)
457 * 10 + 4 = 4574

return 4574

Do you see the pattern? The first number in the equations above is the "current sum". It always starts at 0 and is accumulated in the while loop. Each "subanswer" is the new sum to be used in the next equation.
Hope that helps.

[WaltP]

Make a loop that exits when your value is zero
In the loop, 
    calculate the modulo-10 of the value using % (get the ones digit)
    output the digit
    divide the number by 10
endloop

That's basically it.

[vijayan121]

> calculate the modulo-10 of the value using % ...
the value may be negetive; you need to adjust for that.

al alternative is
a. convert the number to a string
b. reverse the string
c. convert the string back to a number.
eg.

int reverse( int number )
{
  bool negetive = number < 0 ;
  if( negetive ) number = -number ;
  
  ostringstream ostm ;
  ostm << number ;
  string str = ostm.str() ;
  // c++0x => string str = lexical_cast<string>(number) ;
    
  reverse( str.begin(), str.end() ) ;

  istringstream istm(str) ;
  int result ;
  istm >> result ;
  // c++0x => int result = lexical_cast<int>(str) ;

  return negetive ? -result : +result ;
}

[nicz888]

ok, thanks guys.

i think i am going to use the mod 10 step. will post again if i need more help.

two new question on something else.
1)
i am doing a calender program, and the user inputs the first date of that year and the year, and a month. and i am suppose to print out the just that particular month correctly.

here is what i have thought of so far.
user input a year if it is a leap year, it will give me 366 day.
and the first date of that year the user enter will be like 1 for sunday, 2 for monday....

and the print looks like this

S M T W T F S
X X X X X X X

i will use a loop that will print 31 intergers and no more than 7 dates on a line. i will use the number the user input and if it is 1 for monday it will be like one X block. i will just start printing number on second block, but my question is how do a loop that will give me correct block on let said September. i need some how pass the block number to the next month and so forward. thanks.

2)

i have another program that ask the user to input a number, i have set up validation loop
like cin.good() and cin.clear(). but the thing is when ever user inputs a number a variable the validation is not doing it's job.

ex: input: ababa , output: bad input
ex: input: 5a, output: nothing, skips my while loop and go on to the next prompt?
why, thanks again.

looking forward for you guys help thanks.

[WaltP]

1) Calculate the number of days to Sept 1, add the day of the week for Jan 1, divide by 7. Remainder should be the day of the week for Sept 1

2) Line 46 of your validation function should be < not ==. IOW, how are we supposed to know? we ain't psychic! :icon_wink:

[nicz888]

question on the modules % 10;
if i use % 10 on 17 it will only return 7 as the result. how do i get the first digit again.

[WaltP]

Divide by 10 and use % again.