Prime Number Program in C++
Prime Number :
A number which is divisible only by itself and one is called as Prime Number. Let us understand with an example, 7 is a prime number because it is only divisible by only 1 and itself. whereas 9 is not a prime number because it is divisible by 1, 3 & 9.
Program to Check Prime Number
Logic :
- Input a number
- Create a function to check number is prime or not
- Check whether the number is only divisible by 1 and itself or not
- If divisible print prime else print not prime
Code :
#include<bits/stdc++.h>
using namespace std;
int isprime(int a)
{
int i,c=0;
for(i=2;i<=sqrt(a);i++)
{
if(a%i==0)
{
c=1;
break;
}
}
if(c)
{
return 0;
}
return 1;
}
int main()
{
int n;
cin>>n;
if(isprime(n))
{
cout<<"prime";
}
else
{
cout<<"not prime";
}
return 0;
}
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