c - How to use a function recursively? -

i have program prompts user enter 10 digits. program uses function return sum of divisors of each number entered minus , display until number equal 1 or 0. problem function stops after 45's divisors summed. i'm trying use recursion here because function called 'n' number of times until each 1 equal 0 or 1. makes recursion useful in situations these , how can apply here? there i'm missing way function called? can me?

for example,

if user types: 25 -4 6 45 (then presses enter)

the program should output:

25 1 0

-4 0 0

6 6

45 33 15 9 4 3 1 0 0

6 example of perfect number , repeat, if perfect number occurs should stop summing divisors. when sum equal 0 should print once , stop. -4 out of range should print 0. must greater 1.

#include<stdio.h> #include<stdlib.h>    int main(void)   {      //fields     int i=0, j=0, k=0, l=0, num = 0, x = 0, count = 0, total = 0, z = 0;     signed int b[11] = {0};     char discard;       //prompt message     printf( "\n\nplease enter list of numbers: " );       //this while loop scans until enter button pressed     while(i < 11 && (scanf("%d%1[^\n]s", &b[i], &discard)) == 2)     {       ++count;       i++;     }      puts("");     puts("");     //display factors       while(k <= count)     {        x=b[k];       num = sum_divisors(x);       printf("%d " , num);       k++;         puts("");     }      }//end of main      //function sum divisors     int sum_divisors(int a)     {       int total = 0;       int z = 0;        printf("%d ", a);        if(a < 1)       {           total = 0;       }else       {               if((a%1 == 0) && !=1)               total = total + 1;           for(z=2; z<102; z++)          {            if((a%z == 0) && != z)            {              total = total + z;            }//if          }//for       }//end if/else statement       //  printf("%d ", total);        return total;     }//end function sum_divisors 

first, wanted mention few things, first being statement a % 1 == 0 going true positive integer a, , should not used in conditional, other should try avoid using magic numbers, such 102 in loop in sum_divisors; there more natural, , general value used replace 102, , imagine using such constant cause more grief larger numbers divisors larger 102 not calculated.

that being said, way you've structured sum_divisors pretty close how should be, accept missing recursive call , few changes need made make recursive.

• since want print sum of divisors, can't see reason have sum_divisors return value (accept possibly number of times recurred), return value of void seems more appropriate.

• lets rid of (a%1==0)&&(a!=1) , change base case to.

    if( <= 1 )       return; 

  so function knows when stop

• as said earlier, loop can changed more general, no magic numbers. can replace 102 a-1 in order omit counting a divisor, instead of a!=z
• check see if perfect number
• now call recursive call, sum_divisors( total );

another thing initialise total such total = 1,so don't need treat a=1 exception base case.

after said , done, what's left

void sum_divisors( int )  {     int total = 1;     // divisor sum of     int z;      printf("%d ", a);  // print value      if( <= 1 )       // base case         return;      for( z = 2; z < a-1; ++z)  // z < a-1 not include in total     {             if( a%z == 0 )         {             total += z;         }     }        if( total == )   // perfect number we're done         return;      sum_divisors( total ); // call sum_divisors recursively = total } 

it's not different had initially