I'm trying to create a large, multi-file program in C language but I get errors.
The program is actually a smart phone book that can perform multiple tasks like listing, adding, searching for, and deleting names.
For each of those tasks, I created a file that contains the functions and variables required to perform the task.
And here are the files I'm done with coding them:
(1) us-names.txt (a database to store the names):
Mohammed
Ali
Harry
Peter
Hussain
Mark
John
Yu
Mohammed
Christina
Mohammed
Fatima
(2) Request.c file (to receive the request from the user and perform the required task):
#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <stdint.h>
#include <string.h>
//node declaration:
typedef struct node
{
char name[20];
struct node* link;
}
node;
void import_names(void) ;
void add_name(string name) ;
void search_for(string name) ;
void delete_name(string name) ;
int main(int argc , string argv[])
{
//create the hashtable and import the names:
import_names() ;
//check if there is any mistake in the command:
if(argc != 3 || argc != 4)
{
printf("Could not recognize the command, please enter one of the three commands: \n ./phone add name \n ./phone search-for name \n ./phone delete name \n") ;
return 1 ;
}
//otherwise, preform the command:
if(strcmp(argv[1] , "add") == 0)
{
add_name(argv[2]) ;
return 0 ;
}
if(strcmp(argv[1] , "search-for") == 0)
{
search_for(argv[2]) ;
return 0 ;
}
if(strcmp(argv[1] , "delete") == 0)
{
delete_name(argv[2]) ;
return 0 ;
}
else
{
printf("Could not recognize the command, please enter one of the three commands: \n ./phone add name \n ./phone search-for name \n ./phone delete name \n") ;
return 1 ;
}
}
3- Import.c file (to import the names from the text file and hash them and store them in a hashtable) :
#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <stdint.h>
#include <string.h>
//node declaration:
typedef struct node
{
char name[20];
struct node* link;
}
node;
unsigned int hash(char* buffer , unsigned int CAPACITY) ;
void import_names(void)
{
//declarations:
FILE* fp = fopen("us-names.txt" , "a+") ;
if(fp == NULL)
{
printf("CANNOT OPEN THE FILE !\n") ;
fclose(fp) ;
exit ;
}
char buffer[20] ;
unsigned int key = 0;
unsigned int CAPACITY = 100 ;
struct node* temp = NULL ;
struct node* hashtable[CAPACITY] ;
for(int i = 0 ; i < CAPACITY ;i++)
{
hashtable[i] = NULL ;
}
struct node* curr = NULL ;
int num_of_names = 0;
//use a loop to iterate over the FILE:
for(int i = 0 ; !feof(fp) ; i++)
{
//Import name from the FILE & store into buffer:
fgets(buffer , 20 , fp) ;
//pass the name into the hash_function and get the key:
key = hash(buffer , CAPACITY) ;
//put the name in a node then in it's right place in the hashtable using the key:
temp = malloc(sizeof(struct node)) ;
sprintf(temp->name , "%s" , buffer) ;
temp->link = NULL ;
//if the key place of the hashtable is already populated, preform the collision protocol!:
if(hashtable[key] != NULL)
{
for(curr = hashtable[key] ; curr->link != NULL ; curr = curr->link)
{
}
curr->link = temp ;
}
//else if it's unpopulated, just store the name in this place:
else
{
hashtable[key] = temp ;
}
num_of_names++ ;
}
//close the FILE :
fclose(fp) ;
}
4- Hash.c file ( a small file contains a hash function ) :
#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <stdint.h>
#include <string.h>
unsigned int hash(char* buffer , unsigned int CAPACITY)
{
unsigned int sum = 0 ;
for(int i = 0; buffer[i] != '\0' ;i++)
{
sum += buffer[i] ;
}
return sum % CAPACITY ;
}
5- Search.c file ( contains a sort of binary search function to search for any name) :
#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <stdint.h>
#include <string.h>
#include "phonehead.h"
//node declaration:
typedef struct node
{
char name[20];
struct node* link;
}
node;
unsigned int CAPACITY = 100 ;
struct node* hashtable[CAPACITY] ;
unsigned int hash(char* buffer , unsigned int CAPACITY) ;
void search_for(string name)
{
//hash the name to get the place in which the wanted name is stored in the hash function:
unsigned int place = hash(name,CAPACITY);
//go to the location in the hashtable in which the name is stored, and check if the name is in the first node of the chain.
if(strcmp(hashtable[place]->name , name) == 0)
{
printf("FOUND\n") ;
}
//else, go to the node pointed by the current node and check if it contain the wanted name, and repeat this step until reaching null.
else if(strcmp(hashtable[place]->name , name) != 0)
{
struct node* curr = NULL ;
for(curr = hashtable[place]->link ; curr != NULL ; curr = curr->link)
{
if(strcmp(curr->name , name) == 0)
{
printf("FOUND\n");
exit ;
}
}
printf("NOT FOUND!\n") ;
}
}
In addition to a header file :
#include <stdio.h>
#include <stdlib.h>
#include <cs50.h>
#include <stdint.h>
#include <string.h>
typedef struct node
{
char name[20];
struct node* link;
}
node;
unsigned int hash(char* buffer , unsigned int CAPACITY) ;
unsigned int CAPACITY = 100 ;
struct node* hashtable[CAPACITY] ;
void import_names(void) ;
void add_name(string name) ;
void search_for(string name) ;
void delete_name(string name) ;
however when try to link/compile the files using the command
gcc phonehead.h requist.c Import.c Hash.c Search.c -o phone
I receive these errors:
phonehead.h:15:14: error: variably modified ‘hashtable’ at file scope
15 | struct node* hashtable[CAPACITY] ;
| ^~~~~~~~~
In file included from Search.c:6:
phonehead.h:15:14: error: variably modified ‘hashtable’ at file scope
15 | struct node* hashtable[CAPACITY] ;
| ^~~~~~~~~
Search.c:8:16: error: redefinition of ‘struct node’
8 | typedef struct node
| ^~~
