Arduino - How to show a table when you push a button? - button

Question

I want to show a table with certain values when I push a button in arduino-uno.
I have different buttons that are use to read a password, but I need the pinMode(8, INPUT); to show the records.
This code to show the table when I was using the keyboard on the monitor, but I need to change this to use the pinMode(8, INPUT); instead the button 0 of the keyboard.
if (Serial.available()>0) {
incomingByte = Serial.readStringUntil('\n');
Serial.println(incomingByte);
int num=incomingByte.toInt();
if (incomingByte=="0"){
for (int x=0; x<tam;x++){
}
}
Here is more code:
//Pushbutton
Serial.begin(9600);
pinMode(2,INPUT); //button 1
pinMode(3,INPUT); //button 2
pinMode(4,INPUT); //button 3
pinMode(5,INPUT); //button 4
pinMode(6, OUTPUT); //LED RED
pinMode(7, OUTPUT); //LED GREEN
pinMode(8, INPUT); //button to show the tabl
pinMode(11, OUTPUT); //buzzer
}
void loop()
{
pushButton(2,1,0);
pushButton(3,2,1);
pushButton(4,3,2);
pushButton(5,4,3);
if (Serial.available()>0) {
incomingByte = Serial.readStringUntil('\n');
Serial.println(incomingByte);
int num=incomingByte.toInt();
if (incomingByte=="0"){
for (int x=0; x<tam;x++){
}
}
//Funcion pushButton
String pushButton(int pin, int valor, int index)
{
int buttonState=digitalRead(pin);
int state;
String valor_s=String(valor);
state=stateS[index];
switch(state)
{
case 0:
if (buttonState==1){
state=1;
num=num+valor_s;
if (num.length()==4){
Serial.println(num);
for (int i = 0; i < 10; i = i + 1) {
if (client[i]==num){
count[i]=count[i]+1;
found=true;
x=i;
Serial.println("found");
break;
}
} //fin for
//* more code *//
}
} //case 0
break;
case 1:
if (buttonState==0){
state=0;
}
break;
} //switch
stateS[index]=state;
return num;
} //Fin String pushButton