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Source code to check prime no is not working..need assistance in this regard...

#include <iostream> using namespace std; int main() { int num ; int flag=0 int i=2; cout<<"enter no"; cin>>num; while (i< num) { if(num%i==0) { flag=1; break; } i++; } else if(flag==0) cout>>"prime no"; } { else cout<<"not prime"; } return 0; }

31st Oct 2018, 5:00 AM
Usman Zafar
Usman Zafar - avatar
6 odpowiedzi
+ 3
Like I mentioned in my earlier post, your code would say every integer less than 2 is prime, including 0 and 1. But none of them are. To fix this, just add the following before your while loop. if (num < 2) { flag = 1; }
31st Oct 2018, 6:30 AM
Kishalaya Saha
Kishalaya Saha - avatar
+ 3
You wrote a ">>" instead of "<<" and had some braces in the wrong places. Here's a fixed code: #include <iostream> using namespace std; int main() { int num ; int flag = 0; int i = 2; cout << "enter no: "; cin >> num; while (i < num) { if (num % i == 0) { flag = 1; break; } i++; } if (flag == 0) { cout << "prime no"; } else { cout << "not prime"; } return 0; } Note: I didn't change your logic, and currently it would say that all the integers smaller than 2 are primes, whereas none of them are. So you'd need to add an extra if condition for that.
31st Oct 2018, 5:22 AM
Kishalaya Saha
Kishalaya Saha - avatar
+ 2
You're welcome, Usman! :)
31st Oct 2018, 6:54 AM
Kishalaya Saha
Kishalaya Saha - avatar
+ 1
hmmm... its start working...😊 thanks alot sir👍👍
31st Oct 2018, 6:51 AM
Usman Zafar
Usman Zafar - avatar
0
it shows o/p compilation error
31st Oct 2018, 5:00 AM
Usman Zafar
Usman Zafar - avatar
0
//its working but when i enterd 0 it //shows prime no but 0 is not //prime no..how can i make changes #include <iostream> using namespace std; int main() { int num ; int flag; flag=0; int i; i=2; cout<<"enter no\n"; cin>>num; while (i< num) { if(num%i==0) { flag=1; break; } i++; } if(flag==0) { cout<<"prime no="<<num; } else { cout<<"not prime: \n "<<num; } return 0; }
31st Oct 2018, 6:08 AM
Usman Zafar
Usman Zafar - avatar