Arduino Serial Returning unknown value - arduino

Question

So right now that is my code, It is trying to read the different RGB Values for my LED Strip
However, When I get to where I ask for the green value, there is an unknown byte going through and it automatically goes straight to the else part in green();
I didn't input anything yet but Serial says there is something there. What is it?
#define REDPIN 5
#define GREENPIN 6
#define BLUEPIN 3
#define FADESPEED 5 // make this higher to slow down
void setup() {
pinMode(REDPIN, OUTPUT);
pinMode(GREENPIN, OUTPUT);
pinMode(BLUEPIN, OUTPUT);
Serial.begin(9600);
Serial.println("Starting Program....");
start();
}
int g = 0;
char val = 0;
String valstr = "";
void loop(){
if(Serial.available() > 0){
val = Serial.read();
if(val != '\n'){
valstr += val;
}
else{
Serial.println(valstr);
if (valstr != "Yes"){
valstr = "";
start();
}
else{
Serial.print("Now Asking for RGB values: \n");
Serial.println("What is green value: ");
green();
//
//
valstr = "";
// start();
}
valstr = "";
// green();
}
}
}
void start(){
Serial.print("Do you want a new color? Enter Yes/No: ");
}
char gbyte = 0;
String gstr = "";
boolean not_number;
int gnum = 256;
void green(){
if(Serial.available() > 0)
gbyte = Serial.read();
if ((gbyte >= '0') && (gbyte <= '9')) {
gstr += gbyte;
}
else if(gbyte == ' '){
Serial.println("This is not a number! \n");
Serial.println("Enter a valid number!");
gstr = "";
gbyte = Serial.read();
}
else{
Serial.println(gstr);
Serial.println("This is a number");
}
gstr += gbyte;
// gnum = gstr.toInt();
// if((gnum >= 0) && (gnum <= 255))

Answer 1

I think the issue is with the parsing of the integer from the serial port. Arduino has a built-in function for this :
https://www.arduino.cc/en/Reference/ParseInt