Removing a user-inputted digit from a user-inputted number

[takaflaka]

Okay, so this is the program I was assigned to write.
"Delete k-th digit from the natural number n, counting the digits starting from the last digit in the number."

I've written a complete program, but the problem is that when I input the number and the digit I wanted deleted, it won't show me the result. I input 123 for 'n' and 2 for 'k', so I should get 13, but instead I get a blank. I'm not sure where my mistake is as I've tried changing the program at least 10 times, but the problem remains unsolved. Here is the program. Also, for the record, I am only allowed to use functions such as while, do while, and if else. Those are the restrictions for this assignment. I can't use 'for'.

//Deleting k-th digit from 'n' number
#include <iostream>
#include <math.h>
using namespace std;

int main()
{
int n, k, d, i=0;
double m=0, a, b;
cout<<"Enter a value for n: "<<endl;
cin>>n;
cout<<"Enter the digit (k) that you want deleted: "<<endl;
cin>>k;

while(n>0)
{
d=n%10;
m+=d*pow(10,i);


if(i==k)
{
continue;
}

else
{
i++;
a+=m;

}
}


cout<<a<<endl;
system("pause");
return 0;
}

[MistahMoose]

How do you stop your while loop? You do not change n inside the loop therefore you have no way of terminating the loop

edit:(note continue just jumps to the end of the loop statement, not out of the while loop)

[takaflaka]

I thought that 'i' being equivalent to 'k' would mean that the loop would stop... was I wrong? Should I change the condition of the while to something else?

[MistahMoose]

i == k is the condition of your if statement. Which means it will enter if i==k, and do whats in the statement. Which is continue, this doesnt leave the while loop.
If you wanted to leave the loop if i==k you should use break, or change how the logic overall is performed.

Infinite loops altogether arent typically the best idea. You could easily have your while loops terminating condition be:

while(i != k)
{
//do the things

    i++
}

Eliminating the if else altogether and the infinite loop. Because so long as k is greater than 0 i will eventually equal it.

[takaflaka]

Thank you! I actually got an answer.. so the problem was that I was using continue, but now my issue is that I'm not actually getting the CORRECT answer.. I don't think that what I'm using under the while statement is correct.

[ar2007]

try this :

while( n > 0 )
{
          r = n % 10 ;
          n = n / 10 ;

          if( r == k )
          {
                 --i ;
                 r = 0 ;
          }

          m += r * pow( 10 , i ) ;
          ++i ;
}

std::cout << m << '\n' ;

[ar2007]

r = d in your code;

in your code, it lacked the instruction that reduced the number n:

n = n / 10;

[takaflaka]

It still didn't work, unfortunately. I tried inputting 123 and taking away 2, and instead of 13, I got 54.

[ar2007]

work.

#include <iostream>
#include <math.h>

int main()
{
	int n = 0 , r = 0 , m = 0 , k = 0 , i = 0 ;

	std::cin >> n ;
	std::cin >> k ;

	while( n > 0 )
	{
		r = n % 10 ;
		n = n / 10 ;

		if( r == k )
		{
			--i ;
			r = 0 ;
		}

		m += r * pow( 10 , i ) ;
		++i ;
	}

	std::cout << m << '\n' ;
	return 0;
}

123456789
1
23456789

123456
3
12456

delete variable 'a' and go on output 'm'

[takaflaka]

Ohhh, no. I didn't know you initialized every variable to 0. No wonder it didn't work. Thank you so much! I appreciate it!

[ar2007]

 
std::cout << "You are welcome :) \n" ;