C++ Quicksort with vectors - c++

Question

The quicksort function works perfectly fine as ive tried it with the standard array. When using vectors however, I get an error message saying swap function doesnt take 3 arguments. Any help would be appreciated.
void quicksort(vector<int> &vec, int L, int R) {
int i, j, mid, piv;
i = L;
j = R;
mid = L + (R - L) / 2;
piv = vec[mid];
while (i<R || j>L) {
while (vec[i] < piv)
i++;
while (vec[j] > piv)
j--;
if (i <= j) {
swap(vec, i, j); //error=swap function doesnt take 3 arguments
i++;
j--;
}
else {
if (i < R)
quicksort(vec, i, R);
if (j > L)
quicksort(vec, L, j);
return;
}
}
}
void swap(vector<int> v, int x, int y) {
int temp = v[x];
v[x] = v[y];
v[y] = temp;
}
int main() {
vector<int> vec1;
const int count = 10;
for (int i = 0; i < count; i++) {
vec1.push_back(1 + rand() % 100);
}
quicksort(vec1, 0, count - 1);
}

Answer 1

See
void quicksort(vector<int> &vec, int L, int R)
and
void swap(vector<int> v, int x, int y)
The first parameter does not use reference.

Answer 2

Like various comment say, problem is that your version of swap is being confused with std::swap. You can fix it by either moving the implementation of swap before you use it or add a declaration before you use it.
Also per Devin's answer, pass by reference so you get the swapped values back.
Here is the fixed code:
#include <vector>
using namespace std;
void swap(vector<int>& v, int x, int y);
void quicksort(vector<int> &vec, int L, int R) {
int i, j, mid, piv;
i = L;
j = R;
mid = L + (R - L) / 2;
piv = vec[mid];
while (i<R || j>L) {
while (vec[i] < piv)
i++;
while (vec[j] > piv)
j--;
if (i <= j) {
swap(vec, i, j); //error=swap function doesnt take 3 arguments
i++;
j--;
}
else {
if (i < R)
quicksort(vec, i, R);
if (j > L)
quicksort(vec, L, j);
return;
}
}
}
void swap(vector<int>& v, int x, int y) {
int temp = v[x];
v[x] = v[y];
v[y] = temp;
}
int main() {
vector<int> vec1;
const int count = 10;
for (int i = 0; i < count; i++) {
vec1.push_back(1 + rand() % 100);
}
quicksort(vec1, 0, count - 1);
}