Need help breaking down code to smaller parts C - c

Question

I'm pretty new to C so be gentle, somewhy my code doesn't work, be kind and help my figure it out why it doesn't, also if it's possible to make it shorter without making it too complicated, please help in that too.
main.c
#include <stdio.h>
#include <stdlib.h>
#include "swap.h"
#include "magic.h"
int main(int argc, char *argv[])
{
int i,j,count;
int min=atoi(argv[1]);
int max=atoi(argv[2]);
if(min>max)
{
swap(&min, &max);
}
if (min<0)
{
min=1;
}
if(argc<2 || argc>5){exit(EXIT_FAILURE);}
else
{
magic();
}
}
Magic.c
#include <stdlib.h>
#include <stdio.h>
#include magic.h
magic(char *argv[])
{
for(i = min; i<=max; i++)
{
count = 0;
for(j=2; j<=i/2; j++)
{
if(i%j==0)
{
count++;
break;
}
}
if(count==0 && i!= 1 && i!= 0)
printf("%d \n",i);
}
return 0;
}

Answer 1

this is as single file for simplicity
#include <stdio.h>
#include <stdlib.h>
void swap(int *a,int *b){
int c=*a;
*a=*b;
*b=c;
}
void magic(int min, int max);
int main(int argc, char *argv[])
{
int min,max;
if(argc!=3) // (argc<2 || argc>5)
exit(EXIT_FAILURE);
min=atoi(argv[1]);
max=atoi(argv[2]);
if(min>max)
swap(&min, &max);
if (min<0)
min=1;
magic(min,max);
return EXIT_SUCCESS;
}
void magic(int min, int max){
int i,j,count;
for(i = min; i<=max; i++){
count = 0;
for(j=2; j<=i/2; j++) {
if(i%j==0){
count++;
break;
}
}
if(count==0 && i!= 1 && i!= 0)
printf("%d \n",i);
}
}

Answer 2

You have some error in your code :
you are trying to use the variables min, max and countin your function magic however since they are declared in your main function magic does not have knowledge of them.
you should change your main function like :
#include <stdio.h>
#include <stdlib.h>
#include "swap.h"
#include "magic.h"
int main(int argc, char *argv[])
{
int min=atoi(argv[1]);
int max=atoi(argv[2]);
if(min>max)
{
swap(&min, &max);
}
if (min<0)
{
min=1;
}
if(argc<2 || argc>5){exit(EXIT_FAILURE);}
else
{
magic(min, max);
}
return EXIT_SUCCESS;
}
and your magic function :
#include <stdlib.h>
#include <stdio.h>
#include "magic.h"
int magic(int min, int max)
{
int count;
for(int i = min; i<=max; i++)
{
count = 0;
for(int j=2; j<=i/2; j++)
{
if(i%j==0)
{
count++;
break;
}
}
if(count==0 && i!= 1 && i!= 0)
printf("%d \n",i);
}
return 0;
}
In the main function I change magic(); by magic(min, max); to pass parameters to the function which can be retrieve in magic with it's new signature int magic(int min, int max).
Since your magic function return an integer don't forget to specify the return value in the signature of your function.