Prime Number Check Program in C
Prime Number Check Program in C
Here is a simple program in C that checks if a given number is prime:
#include <stdio.h>
int isPrime(int num) {
if (num <= 1) {
return 0;
}
for (int i = 2; i * i <= num; i++) {
if (num % i == 0) {
return 0;
}
}
return 1;
}
int main() {
int num;
printf("Enter a number: ");
scanf("%d", &num);
if (isPrime(num)) {
printf("%d is a prime number.\n", num);
} else {
printf("%d is not a prime number.\n", num);
}
return 0;
}
This program defines a function isPrime
that takes an integer num
as input and returns 1 if num
is prime and 0 otherwise. The isPrime
function uses a simple algorithm to check if num
is divisible by any number from 2 to the square root of num
. If it is divisible by any number in this range, it is not prime. Otherwise, it is prime.
In the main
function, the program prompts the user to enter a number and then calls the isPrime
function to check if the entered number is prime. The program then prints the result.
Please note that this program assumes the input is a positive integer. It does not handle negative numbers or non-integer inputs.
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