simple user directory program

Here's a bit of sample code for adding, searching records in a binary file. If anyone sees anything problematic, please point it out. Thanks.

main.h

Code:

/*******************/
/*   macro guard  */
/*******************/ 

#ifndef __MAINHEADER__
#define __MAINHEADER__

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/********************/
/* UDTs; constants; */
/********************/

typedef struct {

   char name[40];
   char phone1[16];
   char phone2[16];
   char addr[120];
   char city[100];   
   char zipc[10];

} contact;


/***********************/
/* function prototypes */
/***********************/

void showMenu(void);
void showNames(FILE *);
int addListing(FILE *);
void searchList(FILE *);
int deleteListing(FILE *);

#endif

functions.c

Code:

#include "main.h"

void showMenu(void) {

   printf("1) Add listing\n2) Delete listing\n3) Show listing\n4) Search listing\n5) Quit\n\n--> ");
}

void showNames(FILE *f) {

   /* nothing fancy... just print names of
      entries in file */

   char *p;
   contact *tmp = malloc(sizeof(*tmp));
   /* create temporary variable */   
   
   if(tmp) {

      rewind(f);                   /* clear any eof bit and     */
      fseek(f, 0, SEEK_END);  /* find out how many entries exist */

      if((ftell(f) / sizeof(contact)) > 0) {

         rewind(f);
         fseek(f, 0, SEEK_SET);

         while(fread(tmp, sizeof(contact), 1, f) == 1) {
            if((p = strchr(tmp->name, '\n')) != NULL)
               *p = '\0';

            puts(tmp->name);
         }

      } else
          puts("\nthere are no entries to list\n");

      free(tmp);   /* release memory */
      tmp = NULL;
   } 
} 

int addListing(FILE *f) {

   contact *tmp = malloc(sizeof(*tmp));
   int ret = 0;   
   
   if(tmp) {

      system("cls"); /* non-standard function; comment out if needed */

      /* ask for data; side effect of fgets is 
          it stores the newline char.  remove it
          here or during any output */
   
      printf("Enter name: ");
      fgets(tmp->name, sizeof(tmp->name), stdin);

      printf("Enter address: ");
      fgets(tmp->addr, sizeof(tmp->addr), stdin);

      printf("Enter city, state: ");
      fgets(tmp->city, sizeof(tmp->city), stdin);

      printf("Enter phone1: ");
      fgets(tmp->phone1, sizeof(tmp->phone1), stdin);

      printf("Enter phone2: ");
      fgets(tmp->phone2, sizeof(tmp->phone2), stdin);

      printf("Enter zipcode: ");
      fgets(tmp->zipc, sizeof(tmp->zipc), stdin);

      ret = fwrite(tmp, sizeof(contact), 1, f);
      free(tmp);
   }
   
   return ret;
} 

void searchList(FILE *f) {

   char input[3] = { 0 }, *p;
   
   system("cls"); /* non-standard function */

   do {      

      /* loop while option isn't 1-4 */
	     
      printf("1) By name\n2) By city\n3) By state\n4) Go back\n--> ");
      fgets(input, sizeof input, stdin);
	  
      if((p = strchr(input, '\n')) == NULL)
         while(getchar() != '\n'){}

   } while(input[0] < '1' && input[0] > '4');
   
   if(input[0] != '4') {
   
      char *sstr = malloc(200);
      contact *tmp = malloc(sizeof(*tmp));
	  
      if(sstr && tmp) {
	  
         printf("\nQuery: ");
         fgets(sstr, 200, stdin);
		 
         if((p = strchr(sstr, '\n')) != NULL)
            *p = '\0';         

         rewind(f);
         fseek(f, 0, SEEK_SET);

         /* strstr can be used to find partial matches in
             data fields; however, it's case-sensitive
			
             loop through all entries to see if they
             "match" query */

         while(fread(tmp, sizeof(contact), 1, f) == 1) {

            switch(input[0]) {

               case '1' : if(strstr(tmp->name, sstr) != NULL)
                                puts(tmp->name);
                             break;
               case '2' :
               case '3' : if(strstr(tmp->city, sstr) != NULL) {
                               puts(tmp->name);
                               puts(tmp->city);
                             }
                             break;
            }
         }
		 
         free(sstr);
         free(tmp);
      } else 
         puts("\nerror with request\n");
   }
}

int deleteListing(FILE *f) {

   /* deleting a record is a chore; it requires either loading
      all records in memory and re-writing the data file with
      valid records or perhaps creating a temp file, writing only
      valid records, deleting the data file, and then
      renaming the temp file as the data file.

      for now, just set the name field to "deleted"

      code to do:
	  
	     prompt user to identify record to be deleted, find that
	     record, edit the name field, call it a day
   */
   
   puts("\nfunction not implemented\n");
   return 0;
}

main.c

Code:

#include "main.h"

const char *fname = "contact.dat";

int main(void) {

   /* note: program overwrites data file each time it's run;
            bin files may run into issues with padding and/or
            differences in sizeof POD types when moving from
            machine to machine */

   FILE *fp = fopen(fname, "wb+");
   char input[3] = { 0 }, *p;   

   if(fp) {

      for(; ;) {
	     
         showMenu();
         fgets(input, sizeof input, stdin);

         if((p = strchr(input, '\n')) == NULL)
            while(getchar() != '\n'){}

         if(input[0] == '5') break; 

         switch(input[0]) {

	        case '1' : printf("\n%s\n\n", addListing(fp) == 1 ? "added entry" : "file error"); break;
                case '2' : deleteListing(fp); break;
                case '3' : showNames(fp);     break;
                case '4' : searchList(fp);    break;
                default  : printf("\ninvalid command %s\n", input);
         }
 
      }

      fclose(fp);
   }

   puts("\ndone...\n");
   return 0;
}