Arduino StackArray not global - c

Question

I'm coding a project where I read a byte of serial data, convert it to binary and then print it out to Serial. Currently, I'm using a stack to store the binary. However, when I push the binary numbers to the stack, they appear to be pushed in the method I call push() in, but I cannot pop ints from that array outside of that method because there are no elements to pop. Why, and are there any ways to resolve this problem. I thought stacks were reference variables.
void convertToBinary(byte number, StackArray<int> binaryList){
while(number > 0){
int rem = number % 2;
binaryList.push(rem);
number /= 2;
}
}
It pushes this seemingly fine. However when I try to pop it in another method in which I pass the stack to be popped, no elements are there to be popped.
void printToLED(StackArray<int> list){
//digitalWrite(ledPin, HIGH);
while(!list.isEmpty()){
int ledState = list.pop();
//Serial.println(ledState);
if(ledState == 1){
digitalWrite(ledPin, HIGH);
}
else{
digitalWrite(ledPin, LOW);
}
delay(1000);
transitionFlash();
}
}
Since in the setup I specified serial as the stack printer, it gives me this message when I try to pop an element from the stack.
STACK: can't pop item from stack: stack is empty.
EDIT(Full example):
#include <StackArray.h>
StackArray<int> binary;
int ledPin = 13;
byte data = 0;
void setup() {
Serial.begin(9600);
binary.setPrinter(Serial);
pinMode(ledPin, OUTPUT);
}
void transitionFlash(){
for(int i = 0; i < 20; i++){
digitalWrite(ledPin, LOW);
delay(50);
digitalWrite(ledPin, HIGH);
delay(50);
}
}
void convertToBinary(byte number, StackArray<int> binaryList){
while(number > 0){
int rem = number % 2;
binaryList.push(rem);
number /= 2;
}
}
void printToLED(StackArray<int> list){
while(!list.isEmpty()){
int ledState = list.pop();
if(ledState == 1){
digitalWrite(ledPin, HIGH);
}
else{
digitalWrite(ledPin, LOW);
}
delay(1000);
transitionFlash();
}
}
void blink(int times, int duration){
for(int i = 0; i < times; i++){
digitalWrite(ledPin, HIGH);
delay(duration);
digitalWrite(ledPin, LOW);
delay(duration);
}
}
void loop() {
while(Serial.available()){
data = Serial.read();
convertToBinary(data, binary);
printToLED(binary);
blink(10, 500);
}
}

Answer 1

I've resolved this. In order to pass it as a reference variable, I need to add an ampersand to the front, to notify C that it is in fact a reference variable.