Details of students

//  Details
#include<stdio.h>

struct details{
    char name[30];
    int roll;
    char address[50];
    char date_of_birth[20];
};

int main(){
    int num;
    printf("Enter number of student: ");
    scanf("%d", &num);
    getchar();
    struct details ob[num];

    for(int i = 0; i < num; i++){
        printf("\n\nEnter Details of student %d\n\n", i+1);
        printf("Enter name: ");
        gets(ob[i].name);
        printf("Enter your roll: ");
        scanf("%d", &ob[i].roll);
        getchar();
        printf("Enter you address: ");
        gets(ob[i].address);
        printf("Enter your date of birth: ");
        gets(ob[i].date_of_birth);
    }

    for(int i = 0; i < num; i++){
        printf("\n\nDetails of student %d\n", i+1);
        printf("\nName : %s", ob[i].name);
        printf("\nRoll number: %d", ob[i].roll);
        printf("\nAddress: %s", ob[i].address);
        printf("\nDate of Birth: %s", ob[i].date_of_birth);
    }
}