Stray error "\303"

I don’t know what that means but I can’t compile my code

up/* **********************************************************
 * /*                                                          *
 *  Mert Arduino and Tech - YouTube                         *
 *  Remote Controlled Robot Car (TV - Infrared Remote (IR)) *
 *  Please Subscribe for Support - https://goo.gl/RLT6DT    *
 *                                                          *
 ************************************************************/

/* include library */
#include <IRremote.h>

/*
 * If you have no idea about "IRremote" library, you can watch the tutorial below
 * Arduino Tutorial 32: Control your LEDs with TV or IR Remote
 * https://youtu.be/IVToijhx0ck
 */

define IR sensor pin */
int IRsensorPin = 12;
/* define the some functions used by the library */
IRrecv irrecv(IRsensorPin);
decode_results results;

/* define L298N motor drive control pins */
int RightMotorForward = 2;    // IN1
int RightMotorBackward = 3;   // IN2
int LeftMotorForward = 4;     // IN3
int LeftMotorBackward = 5;    // IN4


void setup(){
  
  /* initialize motor control pins as output */
  pinMode(LeftMotorForward,OUTPUT);
  pinMode(RightMotorForward,OUTPUT);
  pinMode(LeftMotorBackward,OUTPUT);
  pinMode(RightMotorBackward,OUTPUT);

  /* start serial communication to see hex codes */
  Serial.begin(9600);
  irrecv.enableIRIn();
}

void loop(){
  
  /* if the sensor is receive any signal */
  if (irrecv.decode(&results)){
    
    /* print the hex code value on the serial monitor */
    Serial.println(results.value);
    delay(5);

    /* resume function according to hex code */
    irrecv.resume();
  }
  
  /* if the incoming data is "defined hex code" then run the motors functions */
  /* instead of zeros "0000", write the hex codes of your remote control */
  if(results.value == 0×FF14E7) MotorForward();
  if(results.value == 0×FF4AB5) MotorBackward();
  if(results.value == 0×FF5AA5) TurnRight();
  if(results.value == 0×FF10EF) TurnLeft();
  if(results.value == 0×FF38C7) MotorStop();
  
}

/* FORWARD */
void MotorForward(){
  digitalWrite(LeftMotorForward,HIGH);
  digitalWrite(RightMotorForward,HIGH);
  digitalWrite(LeftMotorBackward,LOW);
  digitalWrite(RightMotorBackward,LOW); 
}

/* BACKWARD */
void MotorBackward(){
  digitalWrite(LeftMotorBackward,HIGH);
  digitalWrite(RightMotorBackward,HIGH);
  digitalWrite(LeftMotorForward,LOW);
  digitalWrite(RightMotorForward,LOW);
}

/* TURN RIGHT */
void TurnRight(){
  digitalWrite(LeftMotorForward,HIGH); 
  digitalWrite(RightMotorForward,LOW);
  digitalWrite(LeftMotorBackward,LOW);
  digitalWrite(RightMotorBackward,HIGH);
}

/* TURN LEFT */
void TurnLeft(){
  digitalWrite(RightMotorForward,HIGH);  
  digitalWrite(LeftMotorForward,LOW);
  digitalWrite(LeftMotorBackward,HIGH);
  digitalWrite(RightMotorBackward,LOW);
}

/* STOP */
void MotorStop(){
  digitalWrite(LeftMotorBackward,LOW);
  digitalWrite(RightMotorBackward,LOW);
  digitalWrite(LeftMotorForward,LOW);
  digitalWrite(RightMotorForward,LOW);
}

You are using some bizarre symbol × in literals like 0×FF14E7. That’s your \303.

It is supposed to be 0xFF14E7. Good old plain x (or X), not some weird ×.

And why does your code begin with “up”? What is that “up” doing there?

Look at the functions such as DetectButtons : there are weird characters

if (key == ’*’)
...
   Serial.println (“Button Cancelâ€�);

and so on...

I think the code was copied from a website with a different encoding from the one you use on your computer. Try replacing all occurences of “, �, etc to " or ' characters

I did it, now it compiles OK:

#include <LiquidCrystal.h> //Header file for LCD from https://www.arduino.cc/en/Reference/LiquidCrystal
#include <Keypad.h> //Header file for Keypad from https://github.com/Chrisâ€"A/Keypad
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Three columns
// Define the Keymap
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'},
};
byte rowPins[ROWS] = { 0, 1, 2, 3 };// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte colPins[COLS] = { 4, 5, 6, 7 }; // Connect keypad COL0, COL1 and COL2 to these Arduino pins.
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS ); //  Create the Keypad
const int rs = 8, en = 9, d4 = 10, d5 = 11, d6 = 12, d7 = 13; //Pins to which LCD is connected
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
long Num1, Num2, Number;
char key, action;
boolean result = false;

void setup() {
  lcd.begin(16, 2);
  lcd.print("Maxim");
  lcd.setCursor(0, 1);
  lcd.print("calculator");
  delay(5000);
  lcd.clear();
}
void loop() {

  key = kpd.getKey();
  if (key != NO_KEY)
    DetectButtons();
  if (result == true)
    CalculateResult();
  DisplayResult();
}
void DetectButtons()
{
  lcd.clear();
  if (key == '*')
  {
    Serial.println ("Button Cancel");
    Number = Num1 = Num2 = 0;
    result = false;
  }

  if (key == '1') //If Button 1 is pressed
  { Serial.println ("Button 1");
    if (Number == 0)
      Number = 1;
    else
      Number = (Number * 10) + 1; //Pressed twice
  }

  if (key == '4') //If Button 4 is pressed
  { Serial.println ("Button 4");
    if (Number == 0)
      Number = 4;
    else
      Number = (Number * 10) + 4; //Pressed twice
  }

  if (key == '7') //If Button 7 is pressed
  { Serial.println ("Button 7");
    if (Number == 0)
      Number = 7;
    else
      Number = (Number * 10) + 7; //Pressed twice
  }

  if (key == '0')
  { Serial.println ("Button 0"); //Button 0 is Pressed
    if (Number == 0)
      Number = 0;
    else
      Number = (Number * 10) + 0; //Pressed twice
  }

  if (key == '2') //Button 2 is Pressed
  { Serial.println ("Button 2");
    if (Number == 0)
      Number = 2;
    else
      Number = (Number * 10) + 2; //Pressed twice
  }

  if (key == '5')
  { Serial.println ("Button 5");
    if (Number == 0)
      Number = 5;
    else
      Number = (Number * 10) + 5; //Pressed twice
  }

  if (key == '8')
  { Serial.println ("Button 8");
    if (Number == 0)
      Number = 8;
    else
      Number = (Number * 10) + 8; //Pressed twice
  }

  if (key == '#')
  { Serial.println ("Button Equal");
    Num2 = Number;
    result = true;
  }

  if (key == '3')
  { Serial.println ("Button 3");
    if (Number == 0)
      Number = 3;
    else
      Number = (Number * 10) + 3; //Pressed twice
  }

  if (key == '6')
  { Serial.println ("Button 6");
    if (Number == 0)
      Number = 6;
    else
      Number = (Number * 10) + 6; //Pressed twice
  }

  if (key == '9')
  { Serial.println ("Button 9");
    if (Number == 0)
      Number = 9;
    else
      Number = (Number * 10) + 9; //Pressed twice
  }
  if (key == 'A' || key == 'B' || key == 'C' || key == 'D') //Detecting Buttons on Column 4
  {
    Num1 = Number;
    Number = 0;
    if (key == 'A')
    {
      Serial.println ("Addition");
      action = '+';
    }
    if (key == 'B')
    {
      Serial.println ("Subtraction");
      action = '-';
    }
    if (key == 'C')
    {
      Serial.println ("Multiplication");
      action = '*';
    }
    if (key == 'D')
    {
      Serial.println ("Devesion");
      action = '/';
    }
    delay(100);
  }

}
void CalculateResult()
{
  if (action == '+')
    Number = Num1 + Num2;
  if (action == '-')
    Number = Num1 - Num2;
  if (action == '*')
    Number = Num1 * Num2;
  if (action == '/')
    Number = Num1 / Num2;
}
void DisplayResult()
{
  lcd.setCursor(0, 0);   // set the cursor to column 0, line 1
  lcd.print(Num1); lcd.print(action); lcd.print(Num2);

  if (result == true)
  {
    lcd.print(" = ");  //Display the result
    lcd.print(Number);
  }

  lcd.setCursor(0, 1);   // set the cursor to column 0, line 1
  lcd.print(Number); //Display the result
}