prime number program in C

matthughesfan1980's Avatar
Newbie Member
Hello all i am so new and trying to learn while i serve.
I am supposed to write a program that prints out the first n primes, where n is input by the user. I am supposed to write my program in its own directory in three files: primes.h, main.c, and is_prime.c
This is what the output is supposed to look like:


How many do you want to see? 3000

    1:      2
    2:      3
    3:      5
    4:      7
    5:     11
   25:     97
   26:    101
 2998:  27431
 2999:  27437
 3000:  27449
This is the files that I have so far:
#include <stdio.h>
#include <stdlib.h>

int   is_prime(int n);
#include "primes.h"

int is_prime(int n)
   int   k, limit;

   if (n == 2)
      return 1;
   if (n % 2 == 0)
      return 0;
   limit = n / 2;
   for (k = 3; k <= limit; k += 2)
      if (n % k == 0)
         return 0;
   return 1;
#include "primes.h"

int main(void)
   printf("PRIMES WILL BE PRINTED\n\n");
   printf("How many do you want to see?     \n");
   return 0;
I dont know how to link it to the files and what to fill in the main.c file to make it work. Some guidance would be great

Last edited by shabbir; 8May2007 at 08:54.. Reason: Code block
shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
Please use the Code Block when you have code in the posts
Give an appropriate Title. Your title said Visual Basic and you gave the code of C/C++. I edited it for you.
You just happen to post in Introduce yourself and I moved to C-C++ for better response.
Also you had the same post as an article of C-C++

Last edited by shabbir; 8May2007 at 09:02.. Reason: Include 4th point
pradeep's Avatar, Join Date: Apr 2005
Team Leader
Checkout this thread , I hope this will be of help!
DaWei's Avatar, Join Date: Dec 2006
Team Leader
It depends on your compiler. Read your compiler instructions, then if you don't understand them, post back, naming your system and compiler.
aVague's Avatar, Join Date: May 2007
Go4Expert Member
You need to compile them together or what?

if yes, one way is to copy "is_primes.h" and "is_prime.c" in libraly of Builder or visual studio(if you have)
to "include" - you ll find it , where your program(builder/studio) is installed. if you cant (so you have linux and "vim"), then you collect ALL this programs in compiling directory and write, as usual , "gcc..."