How to make program more effective

[alex067]

One of my homeworks required me to create 30 random numbers from 0 - 9 and count how many times each number appeared.

I made a long if-else statement to check each number condition (as can be seen on the code). I'm just wondering if there is a much faster way to do this?

instead of if ( x = 0)
else if (x = 1) ...

/* ==========================================================================================================
File: Number3.cpp
==========================================================================================================
Programmer: Alexandros Panayi
Date: 10/20/2014
Class: CPSC 121 ("Programming Concepts")
Time: TR 2:30 PM
Instructor: Dr. Ray Ahmadnia
Project: Project No. 7

Description:
Use members of <cstring> to manipulate string data


==========================================================================================================
*/

#include <ctime>
#include <iostream>
#include <iomanip>
#include <array>

using namespace std;

void Display(int *x);
void DisplayData(int *x);

struct NUM
{
	int n;
	int freq;
};

NUM ALL[10];

int main()
{
	srand(time(0));

	int random[30];

	for (int i = 0; i < 30; i++) //assign random numbers 0-9 to n
	{
		random[i] = rand() % 10;
	}

	Display(random); // show the random numbers assigned

	cout << endl;

	for (int i = 0; i < 10; i++) //set all numbers to integers from 0 - 9
	{
		ALL[i].n = i;
	}

	for (int i = 0; i < 30; i++)
	{
		if (random[i] == 0)
		{
			ALL[0].freq++;
		}
		else if (random[i] == 1)
		{
			ALL[1].freq++;
		}
		else if (random[i] == 2)
		{
			ALL[2].freq++;
		}
		else if (random[i] == 3)
		{
			ALL[3].freq++;
		}
		else if (random[i] == 4)
		{
			ALL[4].freq++;
		}
		else if (random[i] == 5)
		{
			ALL[5].freq++;
		}
		else if (random[i] == 6)
		{
			ALL[6].freq++;
		}
		else if (random[i] == 7)
		{
			ALL[7].freq++;
		}
		else if (random[i] == 8)
		{
			ALL[8].freq++;
		}
		else if (random[i] == 9)
		{
			ALL[9].freq++;
		}
	}

	DisplayData(random);

	system("PAUSE");
	return 0;

}

void Display(int *x)
{
	for (int i = 0; i < 30; i++)
	{
		cout << i[x] << " ";
	}
}

void DisplayData(int *x)
{
	cout << "\tNUMBER \tFREQUENCY" << endl;
	for (int i = 0; i < 30; i++)
	{
		cout << char(196);
	}
	cout << endl;
	cout << setfill(' ');
	cout << fixed << showpoint << setprecision(2);
	for (int i = 0; i < 10; i++)
	{
		cout << left << setw(10) << ALL[i].n << right << setw(10) << ALL[i].freq;
		cout << endl;
	}
}

[Esslercuffi]

	for (int i = 0; i < 30; i++)
	{
		if (random[i] == 0)
		{
			ALL[0].freq++;
		}
		else if (random[i] == 1)
		{
			ALL[1].freq++;
		}
		else if (random[i] == 2)
		{
			ALL[2].freq++;
		}
		else if (random[i] == 3)
		{
			ALL[3].freq++;
		}
		else if (random[i] == 4)
		{
			ALL[4].freq++;
		}
		else if (random[i] == 5)
		{
			ALL[5].freq++;
		}
		else if (random[i] == 6)
		{
			ALL[6].freq++;
		}
		else if (random[i] == 7)
		{
			ALL[7].freq++;
		}
		else if (random[i] == 8)
		{
			ALL[8].freq++;
		}
		else if (random[i] == 9)
		{
			ALL[9].freq++;
		}
	}

all of that can be accomplished with just:

for (int i = 0; i < 30; i++)
	ALL[random[i]].freq++;

[Ispil]

Well, you could just do...

ALL[random[i]].freq++;

[alex067]

What is the statement, ALL[random[i]].freq++; saying?

I know it says increase the increment by 1 of freq associated with the random number, but I don't see how that works in the statement.

If I'm trying to find the max and min frequency, in other words, which number appears the most and how many times, can I say;

ALL[max[i].n] and
ALL[min[i].n]

to say which number appears the most and the least?

[Esslercuffi]

well look at some part of what you're already doing:

		else if (random[i] == 8)
		{
			ALL[8].freq++;
		}

ALL[8].freq++; is the same as ALL[ random[i] ].freq++;

it just uses the value of a specific element in random, as the index into ALL.

[alex067]

Ah I see, that makes it very clear thank you.

I need to show which number appeared the most and how many times, however when I compile my program, the max number which appears and the min number doesn't show. What's wrong with my condition statement?

#include <ctime>
#include <iostream>
#include <iomanip>
#include <array>

using namespace std;

void Display(int *x);
void DisplayData(int *x);
void FindMaxMin(int *x);

struct NUM
{
	int n;
	int freq;
};

NUM ALL[10];

int main()
{
	srand(time(0));

	int random[30];

	for (int i = 0; i < 30; i++) //assign random numbers 0-9 to n
	{
		random[i] = rand() % 10;
	}

	Display(random); // show the random numbers assigned

	cout << endl;

	for (int i = 0; i < 10; i++) //set all numbers to integers from 0 - 9
	{
		ALL[i].n = i;
	}

	for (int i = 0; i < 30; i++)
	{
		
		ALL[random[i]].freq++;
	}

	DisplayData(random); //display the random numbers and their frequency 

	FindMaxMin(random);

	system("PAUSE");
	return 0;

}

void Display(int *x)
{
	for (int i = 0; i < 30; i++)
	{
		cout << i[x] << " ";
	}
}

void DisplayData(int *x)
{
	cout << "\tNUMBER \tFREQUENCY" << endl;
	for (int i = 0; i < 30; i++)
	{
		cout << char(196);
	}
	cout << endl;
	cout << setfill(' ');
	cout << fixed << showpoint << setprecision(2);
	for (int i = 0; i < 10; i++)
	{
		cout << left << setw(10) << ALL[i].n << right << setw(10) << ALL[i].freq;
		cout << endl;
	}
}

void FindMaxMin(int *x)
{
	int max = 0;
	int min = 9;

	for (int i = 0; i < 10; i++)
	{
		if (ALL[i].freq > max)
		{
			max = ALL[i].freq;
			if (x[i] == max)
			{
				cout << "Number(s) with the largest frequency of " << max << " is/are: " << x[i] << endl;
			}
		}
		if (ALL[i].freq < min)
		{
			min = ALL[i].freq;
			if (x[i] == min)
			{
				cout << "Number(s) with the lowest frequency of " << min << " is/are: " << x[i] << endl;
			}
		}
	}
}