Integers don't show when written into .dat file in c - c

Question

I am trying to write some records (patient info) into a .dat file using c. The patient info contains the National ID no., name, gender and the telephone no.
Here's my code:
#include<stdio.h>
int main(void)
{
char order = 'y';
int nic = 0; // NIC no.
char name[] = "xxx"; // name
char gender = 'x'; // Patients' gender
int tel_no = 0; // telephone no.
FILE *fp;
fp = fopen("patientdetails.dat", "w"); // Creat patientdetails file
if (fp == NULL)
{
printf("Cannot open file\n");
return -1;
}
else
{
printf("Do you want to enter a record (y/n): ");
scanf("%c", &order);
while (order == 'y' || order == 'Y')
{
printf("Enter nic no.: ");
scanf("%d", &nic);
printf("Enter name: ");
scanf("%s", name);
printf("Enter gender (m/f): ");
scanf(" %c", &gender);
printf("Enter tel no.: ");
scanf("%d", &tel_no);
fprintf(fp, "%d %s %c %d\n", nic, name, gender, tel_no);
printf("Do you want to enter a record (y/n): ");
scanf(" %c", &order);
}
fclose(fp);
}
return 0;
}
However when I enter the following info into my .dat file in the terminal:
Do you want to enter a record (y/n): y
Enter nic no.: 200007102766
Enter name: Timothy
Enter gender (m/f): m
Enter tel no.: 0779428897
Do you want to enter a record (y/n): n
There is an error in the integers, namely nic no. and telephone no.
Additionally I made another program to read the file, the error in the integers still seem to show up.
Errors in the .dat file:
7956596 Timothy m 779428897
I can't seem to figure out how to correct the integer errors,
where 20007102766 is shown as 7956596
and 0779428897 is shown as 779428897.
Any help is appreciated!

Answer 1

Your variable byte size is larger than a int, so you should use bigger variable type.
In your example, you can use long type for nic and tel_no veriables.
Also you should use %ld in format, otherwise it gives you warning.
char order = 'y';
long nic = 0; // NIC no.
char name[] = "xxx"; // name
char gender = 'x'; // Patients' gender
long tel_no = 0; // telephone no.
And while formating
printf("Enter nic no.: ");
scanf("%ld", &nic);
printf("Enter tel no.: ");
scanf("%ld", &tel_no);
fprintf(fp, "%ld %s %c %ld\n", nic, name, gender, tel_no);