Lesson 38 Source Code

List of videos 
Lesson 38 Video

Lesson 38: Applying functions

NOTE: for a fast copy, follow these steps in order:

Click anywhere in the text box below (result will be a blinking vertical line in the text box
Hit ctrl + A on the key board (the "ctrl + A" means hit Ctrl and A at the same time)
(The result should be that all the text inside the text box lights up in blue)
Hit Ctrl + C (Nothing significantly happens that is visible) and now its copied to the clipboard and your ready to paste it anywhere you wish


A prime number algorithm


This is an example of a prime number algorithm that is being used inside the main loop..
#include <iostream>
using namespace std;

int main()
{
	int n=13;
	for(int a=2;a<=n;a++)
	{
		if(a==n)
		{
			cout << n << " is PRIME";
			break;
		}
		if(n%a==0)
		{
			cout << n << " is not prime";
			break;
		}
	}
	cin.get();
	return 0;
}

#include <iostream>
using namespace std;

int main()
{
	int n=2;
	while(n < 100)
	{
		for(int a=2;a<=n;a++)
		{
			if(a==n)
			{
				cout << n << " is PRIME\n";
				break;
			}
			if(n%a==0)
			{
				cout << n << " is not prime\n";
				break;
			}
		}
		n++;
	}
	cin.get();
	return 0;
}


OTE: You will have to scroll all the way down on the text boxes to see the main body

Prime function

NOTE: There is a more efficint version of the prime algorithm in one of the ctime library videos
bool Prime(int n)
{
	for(int a=2;a<=n;a++)
	{
		if(a==n)
		{
			return true;
		}
		if(n%a==0)
		{
			return false;
		}
	}
}


Here are some examples that use the Prime function. (You will have to scroll to see the main body of the program)
#include <iostream>
using namespace std;

bool Prime(int n)
{
	for(int a=2;a<=n;a++)
	{
		if(a==n)
		{
			return true;
		}
		if(n%a==0)
		{
			return false;
		}
	}
}

int main()
{
	cout << Prime(17);
	cin.get();
	return 0;
}


This code will print the first 100 prime numbers to the screen
#include <iostream>
using namespace std;

bool Prime(int n)
{
	for(int a=2;a<=n;a++)
	{
		if(a==n)
		{
			return true;
		}
		if(n%a==0)
		{
			return false;
		}
	}
}

int main()
{
	int number=2;
	while(number<100)
	{
		if(Prime(number))
		{
			cout << number << endl;
		}
		number++;
	}
	cin.get();
	return 0;
}


This next two pieces of code are examples of how to print NON-prime numbers to the screen
#include <iostream>
using namespace std;

bool Prime(int n)
{
	for(int a=2;a<=n;a++)
	{
		if(a==n)
		{
			return true;
		}
		if(n%a==0)
		{
			return false;
		}
	}
}

int main()
{
	int number=2;
	while(number<100)
	{
		if(Prime(number)==false)
		{
			cout << number << endl;
		}
		number++;
	}
	cin.get();
	return 0;
}


Here is an application of the NOT (!) operator
#include <iostream>
using namespace std;

bool Prime(int n)
{
	for(int a=2;a<=n;a++)
	{
		if(a==n)
		{
			return true;
		}
		if(n%a==0)
		{
			return false;
		}
	}
}

int main()
{
	int number=2;
	while(number<100)
	{
		if(!Prime(number))
		{
			cout << number << endl;
		}
		number++;
	}
	cin.get();
	return 0;
}


Here is an example of a void function. void functions does NOT take a return type... thats the only difference
void h()
{
	cout << "Hello World\n";
}


Here is an example of using a void type function
#include <iostream>
using namespace std;

bool Prime(int n)
{
	for(int a=2;a<=n;a++)
	{
		if(a==n)
		{
			return true;
		}
		if(n%a==0)
		{
			return false;
		}
	}
}

void h()
{
	cout << "Hello World\n";
}

int main()
{
	h();
	cin.get();
	return 0;
}