program to understand ftell() function

using codeblocks
------------------------------------------------------------------
/*program to 'struct ' concept to store employee id,first name and salary to a data file until you say 'n'.
Then display all those stored records.
*/
#include <stdio.h>
#include<conio.h>
struct employee                           //struct tag
{
    int employee_id;
    float employee_salary;
    char employee_name[50];
}var;                                      //variable
int main()
{
FILE *k;                                  //  pointer for file declaration
char choice;                              //identifier declaration
k=fopen("employees.txt","w");             //file opening in write mode
do
{
printf("\n enter employee id\n");
scanf("%d",&var.employee_id);
printf("enter employee salary\n");
scanf("%f",&var.employee_salary);
printf("enter  employee name\n");       // getting inputs
scanf("%s",var.employee_name);
fwrite(&var,sizeof(var),1,k);; //writing data to data file
printf("want to continue (y/n):=");//prints message
choice=getche();                      //gets a character
}while(choice!='n');        //writing repeats as you enter 'y'
printf("\n writing process completed successfully\n");
rewind(k);
fclose(k);                            //closing of file                                                            //closing data file
printf("-----------------------\n");
printf("reading data\n");             //opening file in read mode
k=fopen("employees.txt","r");               //file opening

while((fread(&var,sizeof(var),1,k))==1)// fread() reads the records till it is true.
                                        //As it becomes less than 1, it stops
{
    printf("employee id=%d,employee salary=%f,employee name=%s\n",var.employee_id,var.employee_salary,var.employee_name);//prints the struct value
}
//location=ftell(k);
printf("the location using ftell=%ld\n",ftell(k));// tells us the location of pointer.
fseek(k,2,SEEK_SET);                               // sets the pointer to second position
printf("the location after using seek_set=%ld\n",ftell(k));
fseek(k,0,SEEK_CUR);                               //takes the current location of pointer.
                                                  //IF we take any other value than 0 ,
                                                   //it adds that to previous location and displays that
printf("the location after using seek_cur=%ld\n",ftell(k));
fseek(k,0,SEEK_END);                               //takes  position of pointer is at the end.
printf("the location after using seek_end=%ld\n",ftell(k));
rewind(k);                                         //takes the pointer to 0 location i.e. beginning
printf("the location=%ld\n",ftell(k));
fclose(k);                            //closing of file.
getch();
return 0;
}
----------------------------------------------------------------------------------------------------------
using turbo c++
-----------------------------------------------------------
/*program to 'struct ' concept to store employee id,first name and salary to a data file until you say 'n'.
Then display all those stored records.
*/
#include <stdio.h>
#include<conio.h>
struct employee                           //struct tag
{
    int employee_id;
    float employee_salary;
    char employee_name[50];
}var;                                      //variable
int main()
{
FILE *k;                                  //  pointer for file declaration
char choice;                              //identifier declaration
k=fopen("employees.txt","w");             //file opening in write mode
do
{
printf("\n enter employee id\n");
scanf("%d",&var.employee_id);
printf("enter employee salary\n");
scanf("%f",&var.employee_salary);
printf("enter  employee name\n");       // getting inputs
scanf("%s",var.employee_name);
fwrite(&var,sizeof(var),1,k);; //writing data to data file
printf("want to continue (y/n):=");//prints message
choice=getche();                      //gets a character
}while(choice!='n');        //writing repeats as you enter 'y'
printf("\n writing process completed successfully\n");
rewind(k);
fclose(k);                            //closing of file                                                            //closing data file
printf("-----------------------\n");
printf("reading data\n");             //opening file in read mode
k=fopen("employees.txt","r");               //file opening

while((fread(&var,sizeof(var),1,k))==1)// fread() reads the records till it is true.
                                        //As it becomes less than 1, it stops
{
    printf("employee id=%d,employee salary=%f,employee name=%s\n",var.employee_id,var.employee_salary,var.employee_name);//prints the struct value
}
//location=ftell(k);
printf("the location using ftell=%ld\n",ftell(k));// tells us the location of pointer.
fseek(k,2,SEEK_SET);                               // sets the pointer to second position
printf("the location after using seek_set=%ld\n",ftell(k));
fseek(k,0,SEEK_CUR);                               //takes the current location of pointer.
                                                  //IF we take any other value than 0 ,
                                                   //it adds that to previous location and displays that
printf("the location after using seek_cur=%ld\n",ftell(k));
fseek(k,0,SEEK_END);                               //takes  position of pointer is at the end.
printf("the location after using seek_end=%ld\n",ftell(k));
rewind(k);                                         //takes the pointer to 0 location i.e. beginning
printf("the location=%ld\n",ftell(k));
fclose(k);                            //closing of file.
getch();
return 0;
}