Now I having another problem with that, after I changed my coding as shown below, it still showing out the error. Inside the coding, there was no any red underline, therefore I can't find out where's the error. So any error of this coding?
struct contact
{
    char name[20],email[20];
    int hpnum;
}add;
int option;
FILE *f;
void addcontact(struct contact list[100]);
void read(struct contact list[100]);
int main (void)
{
    struct contact list[100];
    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);read(list);
        break;
    }
    getch();
}
void addcontact(struct contact list[100])
{
    char name[20],email[20];
    int hpnum,no;
    printf("\nContact Name: ");
    scanf("%s",list[no-1].name);
    fflush(stdin);
    printf("\nHandphone Number: ");
    scanf("%d",&list[no-1].hpnum);
    fflush(stdin);
    printf("\nE-mail: ");
    scanf("%s",list[no-1].email);
}
void read(struct contact list[100])
{
  FILE *f;
  f=fopen("contact.txt","w");
  fwrite(list,sizeof(list),100,f);
  fclose(f);
}
 
     
     
    