the txt file executed some weird character

Question

   struct contact
 {
  char name[20];
  char email[20];
  int hpnum;
 }add;
  FILE *f;

 void addcontact(struct contact list[3]);
 void savecontact(struct contact list[3]);

 int main (void)
 {
    int option,i;
    struct contact list[3];
do
{
    system("cls");
    printf("==========Welcome to Jeffery's Contact System Management==========\n");
    printf("\t\t\tContact System Main Menu\n");
    printf("[1] Create a New Contact\n");
    printf("[2] Modified Existing Contact\n");
    printf("[3] Delete Existing Contact\n");
    printf("[4] Search Existing Contact\n");
    printf("[5] Exit\n");
    printf("Please enter one of your option.\n");
    scanf("%d",&option);

    switch(option)
    {
        //add new contact
        case 1:addcontact(list);savecontact(list);
        break;
        case 2:
        case 3:
        case 4:for(i=0;i<3;i++)
               {
                   if(list[i].email!=0){
                        printf("\nContact Name: %s",list[i].name);
                        printf("\nHandphone Number: %d",list[i].hpnum);
                        printf("\nE-mail: %s",list[i].email);
                   }
               }
               getch();
               break;
        case 5:exit(EXIT_SUCCESS);
    }
}while(i=1);
getch();
}
void addcontact(struct contact list[3])
{
 char name[20],email[20];
 int hpnum,no=0;

 fflush(stdin);
 printf("\nContact Name: ");
 scanf("%s",list[no].name);
 fflush(stdin);
 printf("\nHandphone Number: ");
 scanf("%d",&list[no].hpnum);
 fflush(stdin);
 printf("\nE-mail: ");
 scanf("%s",list[no].email);
   }
   void savecontact(struct contact list[3])
 {
 FILE *f;
 f=fopen("contact.txt","w");
 fwrite(list,sizeof(list),3,f);
 fclose(f);
}

After I added the contact, it does store it when I searching back inside the cmd. And it included the weird word inside the searching contact section when I search the contact. besides, the txt file that it execute, it's nothing inside that what i wrote. It just consist the weird word.

Answer 1

• fflush(stdin); is undefined error. should use fflush(stdout);

• in savecontact() function fwrite(list,sizeof(list),3,f); is wrong. it should be

  fwrite(list, sizeof(struct contact), 3, f);

• Declaration even wrong void addcontact(struct contact list[3]) should be

  void addcontact(struct contact *list)

EDIT

corrected your code. Please read comments I added in your code.

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
struct contact
{
    char name[20];
    char email[20];
    int hpnum;
}add;
FILE *f;
void addcontact(struct contact list[3]);
void savecontact(struct contact list[3]);

int main (void){
    int option  ;
    struct contact list[1]; // chnages the size of Lint to One
    do
    {
        printf("==========Welcome to Jeffery's Contact System Management==========\n");
        printf("\t\t\tContact System Main Menu\n");
        printf("[1] Create a New Contact\n");
        printf("[2] Modified Existing Contact\n");
        printf("[3] Delete Existing Contact\n");
        printf("[4] Search Existing Contact\n");
        printf("[5] Exit\n");
        printf("Please enter one of your option.\n");
        scanf("%d",&option);
        switch(option)
        {
                //add new contact
                case 1:
                             addcontact(list);
                       savecontact(list);
                       break;
                case 2:
                case 3:
                case 4: // read from file instead from memroy (list)
                            f=fopen("contact.txt","rb");
                            while(fread(list,sizeof(struct contact),3,f)>0)
                                printf("%s %d %s\n",list[0].name, list[0].hpnum, list[0].email);
                            fclose(f);
                        break;
                case 5:exit(EXIT_SUCCESS);
        }
    }while(1); // changed to 1 instead i=1 and remove i variable from declaration 
}

void addcontact(struct contact *list) // Declaration corrected
{
    int no=0;
    fflush(stdout); // fflush(stdin); was wrong! (this line not needed here)
    printf("\nContact Name: ");
    scanf("%s",list[no].name);
    fflush(stdout);
    printf("\nHandphone Number: ");
    scanf("%d",&list[no].hpnum);
    fflush(stdout);
    printf("\nE-mail: ");
    scanf("%s",list[no].email);
}

void savecontact(struct contact *list) // Declaration corrected
{
    // remove redeclaration of `File* f`
    f=fopen("contact.txt","ab"); // open file in a+ mode instead w
    fseek(f, 0, SEEK_END); // Added this line to shift to end of file 
    fwrite(list,sizeof(struct contact),3,f); //Corrected this line 
    fclose(f);
}

And its working, A run:

:~$ gcc c.c -Wall
:~$ ./a.out 
==========Welcome to Jeffery's Contact System Management==========
            Contact System Main Menu
[1] Create a New Contact
[2] Modified Existing Contact
[3] Delete Existing Contact
[4] Search Existing Contact
[5] Exit
Please enter one of your option.
1

Contact Name: grijesh

Handphone Number: 123

E-mail: g@123
==========Welcome to Jeffery's Contact System Management==========
            Contact System Main Menu
[1] Create a New Contact
[2] Modified Existing Contact
[3] Delete Existing Contact
[4] Search Existing Contact
[5] Exit
Please enter one of your option.
1

Contact Name: yourname

Handphone Number: 1234

E-mail: your@email
==========Welcome to Jeffery's Contact System Management==========
            Contact System Main Menu
[1] Create a New Contact
[2] Modified Existing Contact
[3] Delete Existing Contact
[4] Search Existing Contact
[5] Exit
Please enter one of your option.
4
grijesh 123 g@123
yourname 1234 your@email

Answer 2

Your are accepting a single contact in addcontact function and is saving 3 objects in savecontact function.

Your addcontact function should be like this

void addcontact(struct contact *list)
{
 char name[20],email[20];
 int hpnum,no=0;

 fflush(stdout);
 printf("\nContact Name: ");
 scanf("%s",list->name);
 fflush(stdout);
 printf("\nHandphone Number: ");
 scanf("%d",&list->hpnum);
 fflush(stdout);
 printf("\nE-mail: ");
 scanf("%s",list->email);
   }

call it like this

struct contact list;
addcontact(&list);