loop & if structure to test whether an input number is prime or composite. code example
Example 1: program to know if a number is prime
#include
using namespace std;
bool Is_Prime(long long x){
if(x%2==0)return false;
for(int i=3;i*i<=x;i+=2)
if(x%i==0)return false;
return true;
}
int main(){
long long x;
cin>>x;
if(Is_Prime(x))cout<<"Is Prime";
else cout<<"Is not Prime";
}
Example 2: prime number c
#include
int main()
{
int i, num, p = 0;
printf("Please enter a number: \n");
scanf("%d", &num);
for(i=1; i<=num; i++)
{
if(num%i==0)
{
p++;
}
}
if(p==2)
{
printf("Entered number is %d "\
"and it is a prime number.",num);
}
else
{
printf("Entered number is %d "\
"and it is not a prime number.",num);
}
}