CodeDay5 < KenyonCpp

Day 5 Sample code

Prime 1 - not quite right

#include<iostream>
 
using namespace std;
 
int main() {
    int num,count=0;
    cout<<"Enter the number to check : ";
    cin>>num;
    int i = 2;
    while (i<num){
        if(num%i==0) {       // checks if the number is fully divisible or not
            count++;
        }
        i++;
    }
    if(count==0) {
        cout<<"It is a Prime Number \n";
    } else {
 cout<<"It is not a Prime Number \n";
    }
}

Prime correct (for 1)

#include<iostream>
 
using namespace std;
 
int main() {
    int num,count=0;
    cout<<"Enter the number to check : ";
    cin>>num;
    
 int i = 2;
    while (i<num){
        if(num%i==0) {       // checks if the number is fully divisible or not
            count++;
        }
        i++;
    }
    if(num < 2 || count>0) {
    	cout << num <<" is not a Prime Number \n";
    } else {
        cout << num <<" is a Prime Number \n";
 }
}

Prime faster

#include<iostream>
 using namespace std;
 
int main() {
    int num,count=0;
    cout<<"Enter the number to check : ";
    cin>>num;
    
   	int i = 2;
    while (i<num && num%i!=0){
        i++;
    }
    if (i==num) {
        cout<<"It is a Prime Number \n";
    } else {
 cout<<"It is not a Prime Number \n";
 cout<<"The Number " << num << " is divisable by " << i << "\n";
 }
 
}

Prime with multiway

#include<iostream>
 using namespace std;
 
int main() {
    int num,count=0;
    cout<<"Enter the number to check : ";
    cin>>num;
    
    int i = 2;
    while (i<num && num%i!=0){
        i++;
    }
    if (num<2) {
    	cout << num << " is not prive by definition";
    } else if (i==num) {
       cout << num <<" is a Prime Number \n";
    } else {
    	cout<<"It is not a Prime Number \n";
    	cout<<"The Number " << num << " is divisable by " << i << "\n";
 	}
}

Prime with for statement

#include<iostream>
 
using namespace std;
 
int main() {
    int num,count=0;
    bool prime = true;
    cout<<"Enter the number to check : ";
    cin>>num;
 
    for(int i=2;i<num;i++){
        if(num%i==0) {       // checks if the number is fully divisible or not
            prime = false;
        }
    }
    if(prime) {
        cout<<"It is a Prime Number \n";
    } else {
 cout<<"It is not a Prime Number \n";
 }
}

Prime with break

#include<iostream>
 
using namespace std;
 
int main() {
    int num,count=0;
    bool prime = true;
    cout<<"Enter the number to check : ";
    cin>>num;
 
        if (num > 1) {
        for(int i=2;i<num;i++){
                if(num%i==0) {       // checks if the number is fully divisible or not
                prime = false;
                break;
                }
        }
        if(prime) {
                cout<<num << " is a Prime Number \n";
        } else {
                        cout<<num << " is not a Prime Number \n";
        }
    } else {
            cout << num << " is not prime by definition";
    }
 
}

Prime using square root

#include<iostream>
 
using namespace std;
#include <math.h>
 
int main() {
    int num,count=0;
    bool prime = true;
    cout<<"Enter the number to check : ";
    cin>>num;
    int max = sqrt(num);
 
 	if (num > 1) {
    	for(int i=2;i<=max;i++){
        	if(num%i==0) {       // checks if the number is fully divisible or not
            	prime = false;
            	break;
        	}
    	}
    	if(prime) {
        	cout<<num << " is a Prime Number \n";
    	} else {
                cout<<num << " is not a Prime Number \n";
    	}
     } else {
 	cout << num << " is not prime by definition";
     }
 
}

Prime list

#include<iostream>
 
using namespace std;
#include <math.h>
 
int main() {
    int max,count=0;
    bool prime = true;
    cout<<"Enter the maximum number to check : ";
    cin>>max;
    
    for (int j=2 ; j<=max; j++) {
    	prime = true;
    	for(int i=2;i<= sqrt(j);i++){
        	if(j%i==0) {      
            	prime = false;
            	break;
        	}
    	}
    	if(prime) {
        	cout << j << " ";
    	} 
    }
    cout << "\nDone listing primes less than or equal to " << max << ".\n";
}

Prime 1

Topic revision: r4 - 2015-09-17 - JimSkon