C program to generate and print all prime numbers between two given integers

Below is the code to print all prime numbers between two integers

#include <stdio.h>
int main(){
    int a,b,i;
    printf("Enter two numbers to find prime numbers between them ");
    scanf("%d %d",&a,&b);
    printf("Prime numbers between %d and %d\n",a,b);
    for(a;a<b;a++){
        int flag=1;
        for(i=2;i<a;i++){
            if(a%i==0){
                flag=0;
            }
        }
        if(flag==1){
            printf("%d\n",a);
        }
    }
    return 0;
}

Output:

Enter two numbers to find prime numbers between them 2
9
Prime numbers between 2 and 9
2
3
5
7