why does it not print prime number till n

Question

// Sample code to perform I/O:

#include <stdio.h>

int main(){

int num,i,j,k,c=0;

scanf("%d", &num);              // Reading input from STDIN

     // Writing output to STDOUT

     for(j=2;j<num;j++)

     {

     for(i=2;i<j;i++)

   {

       if(j%i==0)

       c++;

   }

   if(c==0)

   printf("%d ",j);

     }

}

Answer 1

See, in your code you have not written printf to take input of "n" from the user. I have written the correct code below with printf in bolded form.

// Sample code to perform I/O:

#include <stdio.h>

int main(){

int num,i,j,k,c=0;

printf("Enter n value = ");

scanf("%d", &num);              // Reading input from STDIN

     // Writing output to STDOUT

     for(j=2;j<num;j++)

     {

     for(i=2;i<j;i++)

   {

       if(j%i==0)

       c++;

   }

   if(c==0)

   printf("%d ",j);

     }

}

Answer 2

#include <stdio.h>

int main ()
{
  int num, i, j, k, c = 0;
  printf ("Enter n value = ");
  scanf ("%d", &num);        // Reading input from STDIN
  // Writing output to STDOUT
    for (j = 2; j < num; j++)
    {
        c = 0; // you forgot to reset c
        for (i = 2; i < j; i++)
        {
            if (j % i == 0)
            c++;
        }
        if (c == 0)
            printf ("%d ", j);
    }
}