Program is Closing

Hello guys I need help on this program because everytime the number of students reaches 7+, the program is having a problem and starts closing..

Output of Program

Code:

Name: First Uno
Age: 1
Sex: Male

Name: Second Dos
Age: 2
Sex: Male

Name: Third Tres
Age: 3
Sex: Male

Name: Fourth Quatro
Age: 4
Sex: Male

Name: Fifth Sinco
Age: 5
Sex: Male

Name: Sixth Sais
Age: 6
Sex: Male

Name: Seventh Siete
Age: 7
Sex: Male

Number of Students: 7

Enter Your First Name:

Program.exe has stopped working


Here's my code

Code:

#include <stdio.h>
#include <conio.h>
#include <string.h>
#include <windows.h>
#include <windowsx.h>
 
typedef struct {      //declare a structure
   char fname[30];    //for each student record
   char lname[30];
   int age;
   char sex[30];
}students;            
 
int main(void) {
   FILE *fpIn;
   int i,studnumber,b;
   char buffer[80];
   students stud[4];   //make an array of student records
 
   fpIn=fopen("names.txt","r+");
   if(!fpIn) {
      printf("Error opening file!\n");
      return 1;
   }
   i=0;
   while(fgets(buffer, sizeof(buffer), fpIn))
   {
      sscanf(buffer, "%s %[^,],%d,%s",stud[i].fname,stud[i].lname,&stud[i].age,&stud[i].sex);
      printf("Name: %s %s \nAge: %d \nSex: %s\n\n",stud[i].fname,stud[i].lname,stud[i].age,stud[i].sex);
      ++i;
   }
   studnumber=i;
 
   fclose(fpIn);
   printf("\nNumber of Students: %d \n",studnumber);
   
   fpIn=fopen("names.txt","a"); 
   if(!fpIn){
             printf("Error on opening file!\n");
             return 1;
   }         
   printf("\nEnter Your First Name: ");
   gets(stud[i].fname);
   printf("Enter Your Last Name: ");
   gets(stud[i].lname);
   printf("Enter Your Gender: ");
   gets(stud[i].sex);
   printf("Enter Your Age: ");
   scanf("%d",&stud[i].age);
   printf("Name: %s %s\nAge: %d\nGender: %s\n",stud[i].fname,stud[i].lname,stud[i].age,stud[i].sex);
   fprintf(fpIn,"%s %s,%d,%s\n",stud[i].fname,stud[i].lname,stud[i].age,stud[i].sex);
   fclose(fpIn);
getch();
}

names.txt

Code:

First Uno,1,Male
Second Dos,2,Male
Third Tres,3,Male
Fourth Quatro,4,Male
Fifth Sinco,5,Male
Sixth Sais,6,Male
Seventh Siete,7,Male

Thank you in advance!

> I need help on this program because everytime the number of students reaches 7+,

Have you really understood what the 4 means here?
> students stud[4];

I dont :<

Its working now Thank you ! I changed it to stud[100]