I am having trouble getting this function to work. I am trying to write a median function that takes a user entered array and size, validates that it is correct and then sorts it and displays the median and sorted array. I have tried several different things and no matter what I try I am unable to get this program to work. Any help would be appreciated. Thank you very much.
#include <iostream>
#include <iomanip>
using namespace std;
double median(int n[], int size);
int main(int argc, char** argv) {
cout << "Calculate The Median of an Array" << endl;
cout << "---------------------------------" << endl;
int size, n;
cout << "Array Size (Maximum is Ten)? ";
cin >> size;
if (size > 10 || size < 0) {
cout << "Invalid size. Please Re-enter." << endl;
};
cout << "Array Contents? ";
cin >> n;
if ([n] != size) {
cout << "Invalid Array. Please Re-enter. " << endl;
};
median(n, size);
return 0;
};
double median(int n[], int size) {
// Allocate an array of the same size and sort it.
double* dpSorted = new double[size];
for (int i = 0; i < size; ++i) {
dpSorted[i] = n[i];
};
for (int i = size - 1; i > 0; --i) {
for (int j = 0; j < i; ++j) {
if (dpSorted[j] > dpSorted[j+1]) {
double dTemp = dpSorted[j];
dpSorted[j] = dpSorted[j+1];
dpSorted[j+1] = dTemp;
};
};
};
// Middle or average of middle values in the sorted array.
int median = 0;
if ((size % 2) == 0) {
median = (dpSorted[size/2] + dpSorted[(size/2) - 1])/2.0;
}
else {
median = dpSorted[size/2];
};
cout << "Median of the array " << dpSorted << "is " << median << endl;
};
I am getting the following errors and I cant figure out how to fix them.
34 16 C:\Users\ryanw\Desktop\C++\Labs\Lab 6\main.cpp [Error] invalid
conversion from 'int' to 'int*' [-fpermissive]
and
18 8 C:\Users\ryanw\Desktop\C++\Labs\Lab 6\main.cpp [Note] initializing
argument 1 of 'double median(int*, int)'
I'm inlining the explanations as comments in the code. Here is the array version. I'm keeping it as close to OP's source as possible.
#include <iostream>
#include <iomanip>
using namespace std;
double median(int n[], int size);
int main() { // the parameters asre not being used. You can safely leave them out.
cout << "Calculate The Median of an Array" << endl;
cout << "---------------------------------" << endl;
unsigned int size; // unsigned disallows negative numbers. Lest testing required
int n[10]; // n is an array of 10 elements
cout << "Array Size (Maximum is Ten)? ";
cin >> size;
while (size > 10) { // repeat until user provides a valid size
cout << "Invalid size. Please Re-enter." << endl;
cin >> size;
};
// the above loop will be an infinite loop if the user types in a value
// that cannot be converted into an integer.
cout << "Array Contents? ";
for (unsigned int index = 0; index < size; index++)
{
cin >> n[index];
}
// don't need to test the size. This is ensured by the for loop. Mostly
// for now we are ignoring the simple problem: "what if the user inputs
// a value that is not an integer?
median(n, size);
return 0;
}// don't need ; after function.
double median(int n[], int size) {
// Don't need an array of doubles. Ignoring it.
// assuming the logic here is correct. If it isn't, that's a different
// topic and another question.
for (int i = size - 1; i > 0; --i) {
for (int j = 0; j < i; ++j) {
if (n[j] > n[j+1]) {
int dTemp = n[j];
n[j] = n[j+1];
n[j+1] = dTemp;
};
};
};
// Middle or average of middle values in the sorted array.
double result = 0; //reusing an identifier is a dangerous business. Avoid it.
if ((size % 2) == 0) {
result = (n[size/2] + n[(size/2) - 1])/2.0;
}
else {
result = n[size/2];
};
cout << "Median of the array is " << result << endl;
// it's harder to print out an array than I think it should be.
// Leaving it out for now
// Other than main, a function with a return type must ALWAYS return.
return result;
}
And with std::vector and other library wizardry:
#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
// using namespace std; generally should avoid this
// moving median up here so forward declaration isn't needed
double median(std::vector<int> &n) { //don't need size. Vector knows how big it is
std::sort(n.begin(), n.end()); // use built-in sort function
double result = 0;
auto size = n.size();
if ((size % 2) == 0) {
result = (n[size/2] + n[(size/2) - 1])/2.0;
}
else {
result = n[size/2];
};
// since this function calculates and returns the result, it shouldn't
// also print. A function should only do one thing. It make them easier
// to debug and more re-usable
return result;
}
int main() {
// can chain couts into one
// endl is more than just a line feed and very expensive. Only use it
// when you need the message to get out immediately
std::cout << "Calculate The Median of an Array\n" <<
"---------------------------------\n" <<
"Array Size (Maximum is Ten)? " << std::endl;
unsigned int size;
std::cin >> size;
while (size > 10) {
// here we use endle because we want he user to see the message right away
std::cout << "Invalid size. Please Re-enter:" << std::endl;
std::cin >> size;
};
std::vector<int> n(size);
std::cout << "Array Contents? " << std::endl;
for (int & val: n) // for all elements in n
{
std::cin >> val;
}
std::cout << "Median of the array is " << median(n) << std::endl;
return 0;
}