Scenario
When we want to test whether a number \(p\) is a prime, we need to divide \(p\) with all numbers between \(2\) and \(p-1\). If none of these numbers divides \(p\), then we can conclude that p is a prime.
In the precess, we can use a state variable, e.g. isprime, initially \(1\) (true), to denote that \(p\) is probably a prime.
#include <stdio.h> int main() { int p=101; int i; int isprime = 1; //1 means as if p is probably a prime //scanf("%d",&p); for (i = 2; i < p; i++) if (p % i == 0) isprime = 0; //if i divides p, then p is NOT a prime if (isprime) //isprime == 1 means it IS a prime printf("%d is a prime.\n",p); else printf("%d is a not prime.\n",p); return 0; }
In many similar scenarios, we may use isvalid to denote a possible solution is propably a valid solution.
