Thread: Why is this function not working? Sigh...

Why is this function not working? Sigh...I am getting a warning....warning C4700: local variable 'lowest' used without having been initialized...but I did initialize it at the start...

Code:

double average(int array[], int numts)
{
	int lowest, total = 0, total2 = 0; 
	double avg;

	for (int count = 0; count < numts; count++)
	
		total += array[count];

		total2 = total - lowest;

		avg = total2 / numts;

	  return avg;

}

Because you are doing just what the compiler is telling you that you're doing Try setting lowest to some value, say 0.

Thank you, it took away the warning but it is still not working, do you know why? I am trying to get the average of the test scores after removing the lowest value.

I am new to c++, but I understand what you guys mean concerning the initialization...I changed it to...still not working though, see any other errors in it?

Code:

double average(int array[], int numts)
{
	int lowest = 0, total = 0; 
	double avg;

	for (int count = 0; count < numts; count++)
	
		total += array[count];

		avg = (total - lowest) / numts;

	  return avg;

}

Originally Posted by nadroj

edit: also, i imagine your for loop is not what you intend. the for loop will only execute the next statement, which in this case is the "total +=..." line. you probably want to surround the indented code with a pair of curly braces

Originally Posted by nadroj

also, since this variable never changes, why not make it a constant or simply hard code the value in it, if it is not going to change?

for any number X, X - 0 = X. the number 0 is the "identity" for subtraction: it has no effect. so there is no point in doing "total - lowest" in your code, when lowest is the constant value of 0.

I believe I see what you are saying...But before, when I had no zero, I was getting a warning that lowest wasn't initialized? What else can I initialize zero with?

im saying there is no point in doing the calculation "total - lowest" because since "lowest" is a constant value of zero, the calculation can be simplified to exclude the "- lowest" part. did you fix your initial problem of not having curly braces?

Yes I did (assuming I did it right), I changed it to...

Code:

double average(int array[], int numts)
{
	int total = 0; 
	int lowest = 0;
	double avg;

	for (int count = 0; count < numts; count++)
	{
		total +=array[count];
	}

	avg = (total - lowest) / numts;

	  return avg;
}

This is my full program as it is now...the last function is to remove a student's lowest testscore and then calculate an average, I am thinking that I should compare the testscores to find the lowest but hasn't the selection sort function done that? I even tried returning the "lowest" variable in order to remove it but it didn't work then either...

Code:

/***This program dynamically allocates an array large enough to
hold a user-defined number of test scores***/
#include <iostream>
#include <iomanip>
using namespace std;

//Function prototypes
int getnumtestscores();
void gettestscores(int[], int);
void showArray(int [], int);
void sort(int [], int);
double average(int[], int);


int main()
{
	int numts = getnumtestscores();

	int *testscores = new int[numts];		//To dynamically allocate an array

	gettestscores(testscores, numts);

	cout << "The testscores are: \n"; showArray (testscores, numts);

	cout << "The testscores sorted are: \n"; sort (testscores, numts);

	showArray (testscores, numts);

    cout << "The average of all " << numts << " test scores is: " 
         << fixed << showpoint << setprecision(2)
         << average(testscores, numts);
	cout << endl;

    // Free dynamically allocated array in memory
    delete [] testscores;
    // Make scores point to null
    testscores = 0;

	return 0;
}

int getnumtestscores()
{
    int num;

    cout << "\n How many test scores do you want to enter : ";
    for(;;) // loop forever  ... until return
    { 
        cin >> num;
     
        return num;
    }  
}

void gettestscores(int testscores[], int numts)
{
	cout << "What are the testscores for the students?\n";

	for (int count = 0; count < numts; count++)
	{
		cout << "Testscore " << setw(2) << (count+1) << ":";

		if (testscores < 0)		//Input validation
		{
			cout << "An invalid score was entered, please enter a score more than 0\n";
		}

		cin >> testscores[count];
	}
}

void sort(int array[], int numts)
{
	int lowIndex, lowest;

	for (int count = 0; count < (numts-1); count++)
	{
		lowIndex = count;
		lowest = array[count];
		
		for (int index = count + 1; index < numts; index++)
		{
			if (array[index] < lowest)
			{
				lowest = array[index];
				lowIndex = index;
			}
		}
		array[lowIndex] = array[count];
		array[count] = lowest;
	}

	return;
}

void showArray(int array[], int numts)
{
	for (int count = 0; count < numts; count++)
		cout << array[count] <<" \n";
	cout << endl;
}

double average(int array[], int numts)
{
	int total = 0; 
	int lowest = 0;
	double avg;

	for (int count = 0; count < numts; count++)
	{
		total +=array[count];
	}

	avg = (total - lowest) / (numts-1);

	  return avg;
}

im not sure what you mean about selection sort or returning lowest, in your description of your last post, but oh well.

aside, in your getnumtestscores you dont need to have a loop, as in the first iteration it simply returns, so in every run of the program that for loop has only one iteration, so there is no point of having a loop. that function therfore only has 2 lines of code, which could easily be put into main directly to ask for the number and get it. if you were doing validation of the input (ie a user shouldnt be able to enter 'x' as their input, which you blindly save), then it would be good to have a separate function as you have now, and validate the input, and loop while the input is not valid. so either remove the loop and unnecessary function (no validation) or keep the function, fix the loop to add validation until they enter a positive non-zero integer (validation). a similar case would arise in other cases you get input of numbers.

oh! i just noticed your sort function! this is very difficult to spot because you have more than one statement on a line, at the top of main where you have sort statement and another statement on the same line: one statement = one line, you should follow that. if you sort your list in ascending order then you dont have to find the minimum, you know it is (assuming you correctly implemented sort, which im not checking ), you know the minimum is always the 0th index of your array. since you have this, change your average function to skip this score, that is, start summing at the 1th index, not 0th, and divide by numts-1.

sorry, I made an error there, this is what it is now...

Code:

/***This program dynamically allocates an array large enough to
hold a user-defined number of test scores***/
#include <iostream>
#include <iomanip>
using namespace std;

//Function prototypes
int getnumtestscores();
void gettestscores(int[], int);
void showArray(int [], int);
void sort(int [], int);
double average(int[], int);


int main()
{
	int numts = getnumtestscores();

	int *testscores = new int[numts];		//To dynamically allocate an array

	gettestscores(testscores, numts);

	cout << "The testscores are: \n"; showArray (testscores, numts);

	cout << "The testscores sorted are: \n"; sort (testscores, numts);

	showArray (testscores, numts);

    cout << "The average of all " << numts << " test scores is: " 
         << fixed << showpoint << setprecision(2)
         << average(testscores, numts);
	cout << endl;

    // Free dynamically allocated array in memory
    delete [] testscores;
    // Make scores point to null
    testscores = 0;

	return 0;
}

int getnumtestscores()
{
    int num;

    cout << "\n How many test scores do you want to enter : "; 
    cin >> num;
     
    return num;
   
}

void gettestscores(int testscores[], int numts)
{
	cout << "What are the testscores for the students?\n";

	for (int count = 0; count < numts; count++)
	{
		cout << "Testscore " << setw(2) << (count+1) << ":";

		if (testscores < 0)		//Input validation
		{
			cout << "An invalid score was entered, please enter a score more than 0\n";
		}

		cin >> testscores[count];
	}
}

void sort(int array[], int numts)
{
	int lowIndex, lowest;

	for (int count = 0; count < (numts-1); count++)
	{
		lowIndex = count;
		lowest = array[count];
		
		for (int index = count + 1; index < numts; index++)
		{
			if (array[index] < lowest)
			{
				lowest = array[index];
				lowIndex = index;
			}
		}
		array[lowIndex] = array[count];
		array[count] = lowest;
	}

	return;
}

void showArray(int array[], int numts)
{
	for (int count = 0; count < numts; count++)
		cout << array[count] <<" \n";
	cout << endl;
}

double average(int array[], int numts)
{
	double total = 0;

	for (int count = 0; count < numts; count++)
	
		total +=array[count];

	  return total/numts;
}

im not going to reread the code unless you specifically point out what is different, let me know if you have questions about my previous post, as i think you can solve it from that.