C Program for Prime number Check Whether a Number entered by user is Prime or Not | Print all Prime numbers between given range
We can also say that the numbers which are either divisible by 1 or itself are known as Prime Numbers.
For example 11, 29, 51, etc. are divisible by only 1 & the number itself so this are the example of prime numbers.
C Program:
Check Whether a Number is Prime or Not
#include <stdio.h>
int main()
{
int n, i, flag = 0;
printf("Enter a Number: ");
scanf("%d", &n);
for (i = 2; i <= n / 2; ++i) // condition for non-prime
{
if (n % i == 0)
{
flag = 1;
break;
}
}
if (n == 1) {
printf("1 is neither prime nor composite.");
}
else {
if (flag == 0)
printf("%d is a prime number.", n);
else
printf("%d is not a prime number.", n);
}
return 0;
}
Output:
Enter a Number: 55
55 is not a prime number.
Enter a Number: 137
137 is a prime number.
Print all Prime numbers between given range
#include <stdio.h>
int main()
{
int a, b, i, j, flag;
printf("Enter lower & Upper range value of the interval: ");
scanf("%d %d", &a, &b); // Take 1st input
printf("Prime numbers between %d and %d are: ", a, b);
// Traverse each number in the interval using for loop
for (i = a; i <= b; i++) {
if (i == 1 || i == 0)
continue;
// flag variable to tell if i is prime or not
flag = 1;
for (j = 2; j <= i / 2; ++j) {
if (i % j == 0) {
flag = 0;
break;
}
}
// flag = 1 means i is prime else not prime
if (flag == 1)
printf("%d ", i);
}
return 0;
}
Output:
Enter lower & Upper range value of the interval: 1 20
Prime numbers between 1 and 20 are: 2 3 5 7 11 13 17 19
Enter lower & Upper range value of the interval: 50 70
Prime numbers between 50 and 70 are: 53 59 61 67
No comments: