C: Recursive function into iterative

[gruba]

Homework Statement

Write an iterative function char* conversion(unsigned int num, int base),
that converts an integer num into any base (base <=10).

Homework Equations

The Attempt at a Solution

How to transform the following recursive function conversion() into iterative:

#include <stdio.h>

void conversion(unsigned num, unsigned base)
{
  if (num / base)
    conversion(num / base, base);
  printf("%u", num % base);
}

int main()
{
  unsigned num, base;
  printf("num=");
  scanf("%u", &num);
  do{
     printf("base=");
     scanf("%u", &base);
    }
  while (base < 2 || base > 10);
  conversion(num, base);
  return 0;
}

 

[emin]

When I have convert between recursive and iterative thinking I find it's best to think about:
* what is changing between the function calls
* how do we know when to terminate and return

So in your example with every recursive call to conversion(num, base) you do num/base so this should be done every loop.

You return when num/base truncates to 0 so use this as the condition in your loop.

 

[rcgldr]

If goal is to follow the logic in the recursive function, use an array like a stack, filling the array from [0] to [n-1], printing the array from [n-1] to [0]. Assuming unsigned is 32 bits, you'll need an array of 32 characters to hold the digits for base 2, less for other bases, so make the array size 32 characters.