c - Getting error undefined reference -

diceroll.c

/*diceroll.c -- dice roll simulation */   #include "diceroll.h"   #include <stdio.h>   #include <stdlib.h> //for library function rand()    int roll_count = 0; //external linkage    static int rollem(int sides) /*private file */   {       int roll;        roll = rand() % sides + 1;       ++roll_count;        return roll;   }   int roll_n_dice(int dice, int sides){       int d;       int total =  0;       if(sides < 2){           printf("need @ least 2 sides.\n");           return -2;       }       if(dice < 1){           printf("need @ least 1 dice.\n");           return -1;       }       for(d = 0; d < dice; d++){       total += rollem(sides);       }       return total;   }   

header file

//diceroll.h   extern int roll_count;   extern int roll_n_dice(int dice, int sides);   

the main program

/*manydice.c -- multiple dice rolls     */   /*compile diceroll.c           */   #include <stdio.h>   #include <stdlib.h> //for library funcion srand()   #include <time.h>   //for time()   #include "diceroll.h"   //for roll_n_dice , roll_count    int main(void){       int dice, roll;       int sides;        srand((unsigned int ) time(0)); /*randomized seed*/     printf("enter number of sides per die, 0  stop.\n");     while(scanf("%d", &sides) == 1 && sides > 0){         printf("how many dice ?\n");         scanf("%d", &dice);          roll = roll_n_dice(dice, sides);         printf("you have rolled %d using %d %d-sided dice.\n", roll,           dice, sides);           printf("how many sides ? enter 0 stop.\n"); }   printf("the rollem() funcion called %d times.\n", roll_count);               //used extern variable printf("good fortune you!!!\n");    return 0;   } 

here compiling with

gcc manydice.c diceroll.c 

but keep saying undfined reference roll_count , roll_n_dice

how fix undfined reference though linking both the
source files.

and used 2 times:

gcc sourcefile.c -o sourcefile.o -c  

for manydice , diceroll , compile using object code still getting same error.

i.e:

gcc manydice.c -o manydice.o -c gcc diceroll.c -o diceroll.o -c gcc -o myresult manydice.o diceroll.o