Thread: Number Factorization

Im trying to get a program that reads in a positive integer and prints out all the factors of that integer. I dont know how to word the code to do the division and only print out the factors. Any help would be greatly appreciated.

by seeing if the division gives a whole number

So if I gave you (or your program) 148, what should you (or your program) print? All the possible factors, all the factors paired off, all the prime factors, something else? Once you know what the answers are, you'll know how to do it.

Take a look at the modulus (&#37 operator. For example if you were given the input number 6, and did a loop from 1 to that value(6), and did something like this

Code:

Make sure that the input number is greater than 1, otherwise this is trivial. Test it to make sure.

for (int i = 1; i <= value; i++)
{
    remainder = value % i;
    if (remainder == 0)
    {
        factor1 = i;
        factor2 = value / i;
        printf("FACTOR 1 = %d\n, factor1);
        printf("FACTOR 2 = %d\n, factor2);    
    }
}

well i would divide it with every number between 1 and its self.. so would I set up a loop to keep dividing and then -- for the next number down?

so I am starting with this and i get like 15 errors

Code:

#include <stdio.h>
int main (void){
int i,value,factor1,factor2,remainder;

for (int i=1; i<= value; i++)

    remainder = value % i;
    if (remainder == 0)
    {
        factor1 = i;
        factor2 = value / i;
        printf("FACTOR 1 = %d\n, factor1);
        printf("FACTOR 2 = %d\n, factor2);    
    }
}
system("pause");

return 0
}

Originally Posted by clipsit

so I am starting with this and i get like 15 errors

Code:

#include <stdio.h>
int main (void){
int i,value,factor1,factor2,remainder;

for (int i=1; i<= value; i++)

    remainder = value % i;
    if (remainder == 0)
    {
        factor1 = i;
        factor2 = value / i;
        printf("FACTOR 1 = %d\n, factor1);
        printf("FACTOR 2 = %d\n, factor2);    
    }
}
system("pause");

return 0
}

Well, yeah, I suppose: the body of your for-loop is not in {curly braces}, you don't have any close quotes in your printf statements, you don't have a semicolon after your return statement, you can't declare new variables inside the parentheses of a for() statement, and even if you could you've already got an integer named i. And, system is in the stdlib library, so you would need to include that header file too. I think that's it.

You only need to test up to half the value since nothing greater can possibly divide it evenly.
And you only really need odd numbers (and test 2 separately).

Ok all that is running smoothly now added in some print and scan statements at beginning. How do I get it to not repeat any numbers?

Code:

#include <stdio.h>
int main (void){
int i,value,factor1,factor2,remainder;
printf("Please enter the inter you want to factor.\n");
scanf("%d",&value);

for (i=1; i<=value; i++)
{
    remainder = value % i;
    if (remainder == 0)
    {
        factor1 = i;
        factor2 = value / i;
        printf("FACTOR 1 = %d\n", factor1);
        printf("FACTOR 2 = %d\n", factor2);    
    }
}
system("pause");

return 0;

}

for example when run with 10
i get
1
10
2
5
5
2
10
1

only guideline is "Create a list of each of the positive factors of the given integer"

sorry Im still really new how do i terminate the loop. I set up the if statement but dont know where to go from there.