How to check if a number is prime in C++ | How to generate Armstrong numbers in C++?

How to check if a number is prime in C++ 

Prime Numbers

Prime numbers are numbers which have only 2 distinct factors i.e 1 and the number itself. Eg. 2,3,5,7,19 etc.

Ques1. Write a program to check if a number is prime or not.
#include <iostream>
#include<cmath>
using namespace std;
int main() {
int n;
cin>>n;
bool flag=0;
for(int i=2;i<=sqrt(n);i++){
if(n%i==0){
cout<<"Non-prime"<<endl;
flag=1;
break;
}
}
if(flag==0){
cout<<"prime"<<endl;
}
return 0;
}

How to generate Armstrong numbers in C++

Armstrong Numbers

Armstrong numbers are numbers which have their sum of cube of individual digits equal to the number itself.
E.g 153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153.

#include <iostream>
#include<math.h>
using namespace std;
int main() {
int n;
cin>>n;
int sum=0;
int originaln=n;
while(n>0){
int lastdigit= n%10;
sum+= pow(lastdigit,3);
n=n/10;
}
if(sum==originaln){
cout<<"Armstrong number"<<endl;
}
else{
cout<<"not armstrong"<<endl;
}

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