- To print prime numbers between 1 & N
User Input: 12
Output: 2,3,5,7,11
#include <iostream>
using namespace std;
int prime(int n){
if(n<2)return 0;
for(int i=2; i<=n/2; i++) {
if(n%i==0) return 0;
}
return 1;
}
int main() {
int num;
cout<<"Enter any +ve number : ";
cin>>num;
cout<<"Your prime numbers between 1 & "<<n<<" are : \n";
for(int i=2; i<num; i++)
if(prime(i))cout<<i<<" ";
return 0;
}
Enter any +ve number : 20 Your prime numbers between 1 & 20 are : 2 3 5 7 11 13 17 19Program
You should know first :
Prime numbers: Numbers greater than 1 & have only 2 factors ( 1 and itself )
Main Logic to check prime :
int prime(int n){
for(int i=2;i<=n/2;i++) {
if(n%i==0) return 0;
}
return 1;
}
We are running the loop n/2
Since, any number can have only factors under its half, except itself
To print all primes :
for(int i=2; i<num; i++) {
//check every number for prime [ if(prime(i)) ], if prime then print the number
}
Concept
Coming Soon !
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