Evaluation function parameters in C++

#include<iostream>
using namespace std;

void test_function(int x, int y, int z){
   cout << "The value of x: " << x << endl;
   cout << "The value of y: " << y << endl;
   cout << "The value of z: " << z << endl;
}

main(){
   int a = 15;
   test_function(a++, a++, a++);
}