Counting the frequency of an elements in an array - c++

Question

Hello I am currently stuck on a homework problem as I have no idea how exactly to approach the problem.
Write a program that reads in a list of integers into an array with base type
int. Provide the facility to either read this array from the keyboard or
from a file, at the user’s option. If the user chooses file input, the program
should request a file name. You may assume that there are fewer than 50
entries in the array. Your program determines how many entries there are.
The output is to be a two-column list. The first column is a list of the distinct
array elements; the second column is the count of the number of
occurrences of each element. The list should be sorted on entries in the
first column, largest to smallest.
So I were to enter: 1, 2, 1, 10, 15, 12, 2, 10, 10
The program should output something like:
List Frequency
1-----2
2-----2
10----3
15----1
I am able to sort the numbers but don't know how I would go about comparing the numbers in the array.
#include <iostream>//Input/Output Library
#include <cstdlib>
#include <iomanip>
using namespace std;//Namespace of the System Libraries
//Global Constants
const int MAX = 10;
//Function Prototypes
void input(int array[], int size);
void sort(int array[],int size);
int main(int argc, char** argv){
//Declare Variable
int array[MAX];
int size = MAX;
//Input Data
input(array, size);
sort(array, size);
cout<<"\nSort Frequency\n";
for(int i = 0; i<size; i++){
cout<<array[i]<<endl;
}
return 0;
}
void input(int a[], int size){
cout<<"Enter "<<size<<" numbers for the array: \n";
for(int i=0; i<size; i++){
cin>>a[i];
}
}
void sort(int a[],int n){
for(int i=0;i<n-1;i++){
for(int j=i+1;j<n;j++){
if(a[i]>a[j]){
a[i]=a[i]^a[j];
a[j]=a[i]^a[j];
a[i]=a[i]^a[j];
}
}
}
}

Answer 1

In addition to #stryku's answer since you only want to print frequencies, you don't even need to create the v vector:
#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <map>
int main() {
std::map<int, size_t> counts;
std::for_each(std::istream_iterator<int>(std::cin), std::istream_iterator<int>(), [&counts](int k) {
++counts[k];
});
for(const auto &pair : counts)
std::cout<<pair.first <<" "<< pair.second<<"\n";
return 0;
}

Answer 2

Here you go (:
#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <map>
int main() {
std::vector<int> v;
std::map<int, size_t> counts;
std::copy(std::istream_iterator<int>(std::cin),
std::istream_iterator<int>(),
std::back_inserter(v));
for(const auto &number : v)
++counts[number];
for(const auto &pair : counts)
std::cout<<pair.first <<" "<< pair.second<<"\n";
return 0;
}
I think your teacher will be surprised if you would explain it to him