Vector::push_back not storing values in vector - c++

Question

Recently I've been trying to write a neural network program. I have all a neurons connections stored in a vector in the neuron. However whenever I push back a connection into the vector it doesn't seem to store (I can tell via debug mode), and when I try to add up the activation values of the vectors in a for loop, I get an out_of_range error. Here's my code.
Main.cpp
#include <iostream>
#include "neuron.h"
void displayboard(bool board [8][8]);
using namespace std;
int main()
{
int id = 2;
int inputids [] = {3};
int outputids [] = {4};
int inputweights [] = {5};
bool new_neuron = true;
neuron test (inputids, outputids, inputweights, new_neuron, id);
test.connections.at(0).value = 6;
// here is where the error is returned
test.activation();
cout << test.activationnumber;
return 0;
}
And here's Neuron.cpp:
#include "neuron.h"
#include <vector>
#include <random>
#include <ctime>
using namespace std;
neuron::neuron(int inputids [], int outputids [], int inputweights [],
bool new_neuron, int id)
{
this->id = id;
if (new_neuron==true) {
srand (time(0));
connection tempconnection;
for (int i = 0; i <=(sizeof (inputids)/sizeof (inputids [0])); i++)
{
tempconnection.type=false;
tempconnection.tofrom = inputids [i];
tempconnection.weight = rand ();
this->connections.push_back (tempconnection);
}
// this continues on for other options
}
void neuron::activation (){
for (int i=0; i<=this->connections.size (); i++) {
this->activationnumber += ((this->connections.at(i).value)
*(this->connections.at (i).weight));
}
}

Answer 1

UPDATE: Reading this will help you understand why your "sizeof/sizeof" approach is not good in C++.
Original answer
The behavior of sizeof(array)/sizeof(array[0]) might not be what you expected. The following code outputs 2 but you seem to expect 4. Use array for objects in the stack or vector for objects in the heap.
#include <iostream>
using namespace std;
void foo( int array[] )
{
wcout << sizeof( array ) / sizeof( array[ 0 ] );
}
int main()
{
int test[ 4 ];
foo( test );
return 0;
}
Change
int inputids [] = {3};
int outputids [] = {4};
to
vector< int > {3};
vector< int > {4};
Also change
neuron(int inputids [],int outputids [] …
{
…
for (int i = 0; i <= …; i++)
…
tempconnection.tofrom = inputids [i];
to
neuron( vector< int > & inputids, vector< int > & outputids …
{
…
for( auto id : inputids )
…
tempconnection.tofrom = id;