C++ templated function causing linking errors
class mergeSort.cpp
Code:
#include <iostream>
#include <vector>
#include "mergeSortContainer.cpp"
using namespace std;
template void merge<vector<int>::iterator>(vector<int>::iterator begin, vector<int>::iterator mid, vector<int>::iterator end, bool (*compare)(int &x, int &y));
template void mergeSort<vector<int>::iterator>(vector<int>::iterator begin, vector<int>::iterator end, bool (*compare)(int &x, int &y));
bool exCompare(int &a, int &b);
bool exCompare(int &a, int &b) {
return (a<b);
}
int main(){
vector<int> vec;
vec.push_back(5);
vec.push_back(7);
vec.push_back(6);
vector<int>::iterator it = vec.begin();
vector<int>::iterator it2 = vec.end();
mergeSort<vector<int>::iterator>(it, it2, exCompare);
return 0;
}
class mergeSortContainer.cpp:
Code:
#include <iostream>
using namespace std;
template <typename I>
void merge(I begin, I mid, I end, bool (*compare)(typename I::value_type &x, typename I::value_type &y)) {
//Get the lengths of the left and the right part.
int n1 = mid - begin;
int n2 = end - mid;
typedef typename I::value_type T;
T* left = new T[n1];
T* right = new T[n2];
int i;
//populate left and right arrays
i = 0;
for (I p=begin;i<n1;p++) {
left[i] = *p;
i++;
}
i = 0;
for (I p=(mid);i<n2;p++) {
right[i] = *p;
i++;
}
T* result;
i = 0;
int leftCtr = 0;
int rightCtr = 0;
//Merge the two sorted arrays
for (;i<n1+n2;i++) {
if (leftCtr<n1 && rightCtr<n2) {
if (compare(left[leftCtr],right[rightCtr])) {
result[i] = left[leftCtr++];
}
else result[i] = right[rightCtr++];
}
else if (leftCtr<n1)
result[i] = left[leftCtr++];
else
result[i] = right[rightCtr++];
}
i = 0;
//Copy the sorted array back into the original array.
for (I p=begin;p!=end;p++) {
*p = result[i++];
}
}
template<typename I>
void mergeSort(I begin, I end, bool (*compare)(typename I::value_type &x, typename I::value_type &y)) {
int len = end - begin;
if (len>1) {
I mid = begin + len/2;
//Sort both the halves
mergeSort(begin, mid, compare);
mergeSort(mid, end, compare);
merge(begin, mid, end, compare);
}
return;
}
when I compile this program I get a long list of what appear to be linker errors. I am using a linux gcc compiler. Any ideas of how I can fix this?
