ช่วยทีค่ะerror2ตัวค่ะ c++เพิ่งหัดเขียนแล้วรันไม่ผ่านค่ะอาจารย์ให้ทำส่งด้วยค่ะ

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

struct employee{
char emp_id[5];
char name[10];
char surname[20];
char position[20];
float salary;
}emp;

void insert_data();
void delete_data();
void search_data();

main() {
int choice;
char temp[] = {0};
do{
clrscr ();
printf ("#################################\n") ;
printf ("# Welcome to employee system #\n");
printf ("#################################\n") ;
printf ("#please select choice #\n") ;
printf ("#1. Insert Data #\n") ;
printf ("#2. Delete Data #\n") ;
printf ("#3. Search Employee Data #\n") ;
printf ("#4. Exit #\n") ;
printf ("################################\n") ;
printf ("Please select choice (1-4 only) :") ;
gets(temp);
choice =atoi(temp);
if(choice==1)insert_data ();
else if(choice==2)delete_data ();
else if(choice==3)search_data ();
}while(choice!=4);
}
void insert_data(){
FILE *fp;
char ans;
char temp[]={0};

if ((fp=fopen("emp loyee.txt","ab"))==NULL) {
printf ("Cannot open file for inert data\n");
getch();
exit(1);
}
do{
printf ("\n\nPlease insert emp loyee data\n");
printf ("Emp loyee Id :");gets(emp.emp_id);
printf ("Name :");gets(emp.name);
printf ("Surname :");gets(emp.surname);
printf ("Position :");gets(emp.position);
printf ("Salary :");gets(temp);
emp.salary=atof(temp);
fwrite(&emp,sizeof(emp),1,fp);
if (ferror(fp)){
printf ("Error for insert data\n") ;
getch ( ) ;
exit (1) ;
}
printf ("Continue (press C) Or Exit (press E) :") ;
ans = getche();
}while(ans!='E');
fclose(fp);
}
void delete_data ( ) {
FILE *fp ;
int i=0 ;
char ans ;
char rec [5] ;
if ((fp=fopen ("emp loyee.txt","rb+"))==NULL) {
printf ("Cannot open file for delete data\n");
getch ();
exit(1);
}
printf ("\n\nThis is emp loyee for delete\n") ;
do{
while (1) {
fread (&emp,sizeof(emp),1,fp) ;
if (ferror (fp)) {
printf ("Error to read data for delete\n") ;
getch ( ) ;
exit (1) ;
}
if (feof (fp))
break ;
++i ;
printf ("%d . %s \t \t", i ,emp . emp_id) ;
}
printf ("\nDo you want to delete data (Y or N) :") ;
ans = getche ();
if (ans=='Y') {
printf ("\nEnter record number :") ;
gets (rec) ;
fseek (fp, ((atoi (rec) -1)*sizeof (emp)) , SEEK_SET) ;
strcpy(emp.emp_id,"\n");
fwrite (&emp , sizeof (emp) , 1 , fp) ;
if (ferror (fp)) {
printf ("Error for delete data\n") ;
getch ( ) ;
exit (1) ;
}
printf ("Delete data complete\n") ;
}
printf ("\nContinue (press C) or Exit (press E) :");
ans = getche ();
printf ( "\n") ;
}while (ans !='E') ;
fclose (fp) ;
}
void search_data(){
FILE *fp ;
char ans ;
char id[5] ;
if ((fp=fopen("emp loyee.txt","rb"))==NULL){
printf ("Cannot open file for search data\n") ;
getch ();
exit (1) ;
}

do{
printf ("\n\nPlease enter employee id for search :") ;
scanf ("%s" , id) ;

while(1){
fread (&emp , sizeof (emp) , 1 , fp) ;
if (ferror (fp)) {
printf ("Error for search data\n") ;
getch ( ) ;
exit (1) ;
}
if (feof(fp)) break ;
if (strcmp(id,emp.emp_id)==0){
printf ("Data Found ! ! ! \n") ;
printf ("Emp loyee Id :%s\n" , emp . emp_id) ;
printf ("Name :%s\n" , emp . name) ;
printf ("Surname :%s\n" , emp . surname) ;
printf ("Position :%s\n" , emp . position) ;
printf ("Salary :%2f\n\n" , emp . salary) ;
break ;
}
}
if (strcmp(id,emp.emp_id)!=0)
printf ("NO emp loyee in emp loyee id %s\n\n" , id) ;
printf ("Continue (press C) Or Exit (press E) :") ;
rewind (fp) ;
ans=getche();
printf ("\n") ;
}while (ans !='E') ;
fclose (fp) ;
}
_______________________________________________
นี่ตัวerrorค่ะ

Compiling 1.CPP:
Warning 1.CPP 38: Function should return a value in function main()
Error 1.CPP 98: Call to undefined function 'strcpy' in function delete_data()
Error 1.CPP 135: Call to undefined function 'strcmp' in function search_data()