Find Prime Factors Of Given NUmber

how to write i tried as follows but it prints all numbers.
i want to print only prime factors of number, also i want it using for loop not while loop can anyone help me. also plz explain me each step bcoz im new in using for loop

Code:

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#include<stdio.h>int main(){
  int num,i=1,j,k;
  printf("\nEnter a number:");
  scanf("%d",&num);
  for(i=1;i<=num;i++){
if(num%i==0)
prime(i);
printf("%d\n",i);
}
}
prime(int i)
{
    int j,flag;
    for(j=2;j<i;j++)
    {
        if(j%i==0)
        flag=1;
        break;
        if(flag==1)
        return 0;
        return i;
    }
}

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You can actually structure this algorithm in such a way that a primality test is not necessary. Simply find the smallest number that divides num, and then divide as much as you can, so that the divisor HAS to be prime.

Code:

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void factorize(long num)
{
    long i = 2;
    while(num > 1) {
        while(num % i == 0) {
            num /= i;
            printf("%d  ", i);
        }
        ++i;
    }
    printf("\n");
}

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Hodor likes prime numbers. They are the only real natural numbers after all.