c program to check prime number

1int isPrime(long long number) {
2
3	if (number == 0 || number == 1 || (number % 2 == 0 && number > 2)) {
4		return 0;
5	}
6
7	else {
8		for (long long i=3; i <= (long long)sqrt(number)+1; i++) {
9			if (number % i == 0) {
10				return 0;
11			}
12		}
13		return 1;
14	}
15}

1#include<stdio.h>
2main() {
3    int n, i, count=0;
4    printf("Enter Number");
5    scanf("%d",&n);
6   
7    for ( i = 1; i<= n; i++) {
8        if (n % i == 1) {
9            count++;
10        }
11    }
12    if( count == 2) {
13        printf("Prime Number");
14    }
15    else {
16        printf("Not A  Prime Number");
17    }
18}

1#include <stdio.h>
2int main() {
3    int n, i, flag = 0;
4    printf("Enter a positive integer: ");
5    scanf("%d", &n);
6
7    for (i = 2; i <= n / 2; ++i) {
8
9        // condition for non-prime
10        if (n % i == 0) {
11            flag = 1;
12            break;
13        }
14    }
15
16    if (n == 1) {
17        printf("1 is neither prime nor composite.");
18    }
19    else {
20        if (flag == 0)
21            printf("%d is a prime number.", n);
22        else
23            printf("%d is not a prime number.", n);
24    }
25
26    return 0;
27}
28

1int isPrime(int n) {
2  for (int i = 2; i < n; i++) if (n % i == 0) return 0; 
3  return 1;
4}

1//program to find prime number or not using c programming
2#include<stdio.h>
3#include<conio.h>
4    void main(){
5    int n; 
6    int prime=1;
7    printf("Enter the number\n");
8    scanf("%d",&n);
9    for (int i= 2; i<n; i++){
10        if(n%i==0){
11            prime=0;
12            break;
13        }
14    }
15        if(prime==0 ){
16            printf(" %d is not prime number.\n",n);
17        }
18    else{
19         printf(" %d is prime number\n",n);
20    }
21
22    getch();
23    }

1//program to find prime number or not using c programming
2#include<stdio.h>
3#include<conio.h>
4// program starts from here after main() function
5    void main(){
6    int n; 
7    int i,count =0;
8    // count is incremented when the loop is true.
9    printf("Enter the number\n");
10    scanf("%d",&n);
11    for (i=1; i<=n; i++){
12        if(n%i==0){
13            count++;
14        }
15    }
16     // for the prime number the no of count is 2
17     // number is divided by 1 or itself(given number) so count ==2
18        if(count ==2){
19            printf("%d is prime number.\n",n);
20        }
21        
22    // for the composite number the number is divided by more than 2 number.
23    else{
24         printf("%d is not prime number\n",n);
25    }
26
27    getch();
28    }
29