Simple implementation about Selection Sort in C++

SelectionSort.cpp

#include <iostream>
#include <vector>
#include <ctime>

// A random number generator
void fillRandom(vector<int> &iArray)
{
 srand((unsigned)time(0));
 for(int i = 0; i < iArray.size(); i++)
 {
  iArray[i] = rand();
 }
}

// Selection sort from biggest to smallest
template <typename Comparable>
void selectionSort(vector<Comparable> &a, int last)
{
 if(last <= 0)
 {
  return;
 }
 
 vector<Comparable>::size_type largest = a[0];
 int index = 0;
 for(int i = 1; i <= last; i++)
 {
  if(a[i] > largest)
  {
   largest = a[i];
   index = i;
  }
 }
 
 vector<Comparable>::size_type buffer = a[index];
 a[index] = a[last];
 a[last] = buffer;
 selectionSort(a, last - 1);
}

// Selection sort from smallest to biggest
template <typename Comparable>
void selectionSortInvert(vector<Comparable> &a, int first)
{
 if(first >= a.size())
 {
  return;
 }
 
 Comparable smallest = a[first];
 int index = first;
 for(int i = first + 1; i < a.size(); i++)
 {
  if(a[i] < smallest)
  {
   smallest = a[i];
   index = i;
  }
 }
 
 vector<Comparable>::size_type buffer = a[index];
 a[index] = a[first];
 a[first] = buffer;
 selectionSortInvert(a, first + 1);
}