#include <LiquidCrystal_I2C.h>
#include <Keypad.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
{'1','2','3','+'},
{'4','5','6','-'},
{'7','8','9','*'},
{'C', '0','=','/'}};
byte rowPins[ROWS] = {5, 4, 3, 2};
byte colPins[COLS] = {A3, A2, A1, A0};
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
String inputString = "";
void messageScreen() {
lcd.print(" A-B-C's");
lcd.setCursor(3, 1);
String message = "Calculator";
for (byte i = 0; i < message.length(); i++) {
lcd.print(message[i]);
delay(50);
}
delay(500);
}
void updateCursor() {
if (millis() / 250 % 2 == 0 ) {
lcd.cursor();
} else {
lcd.noCursor();
}
}
char operation = 0;
String memory = "";
String current = "";
int calculate(char operation, int left, int right) {
switch (operation) {
case '+':
return left + right;
case '-':
return left - right;
case '*':
return left * right;
case '/':
return left / right;
}
return 0; // Default case, should not happen if the input is correct
}
void inputs(char buttn) {
if ('C' == buttn) {
// Clear the input when 'C' is pressed
current = "";
memory = "";
operation = 0;
lcd.clear();
lcd.setCursor(1, 0);
}
else if ('-' == buttn && current == "") {
current = "-";
lcd.print("-");
}
else if (buttn == '+' || buttn == '-' || buttn == '*' || buttn == '/') {
if (current != "") {
if (memory == "") {
memory = current;
current = "";
}
else {
int leftNum = memory.toInt();
int rightNum = current.toInt();
memory = String(calculate(operation, leftNum, rightNum));
current = "";
lcd.clear();
lcd.setCursor(1, 0);
lcd.print(memory);
}
}
operation = buttn;
lcd.setCursor(0, 1);
lcd.print(buttn);
lcd.setCursor(current.length() + 1, 1);
}
else if (buttn == '=') {
if (current != "" && memory != "" && operation != 0) {
int leftNum = memory.toInt();
int rightNum = current.toInt();
memory = String(calculate(operation, leftNum, rightNum));
lcd.clear();
lcd.setCursor(1, 0);
lcd.print(memory);
lcd.setCursor(0, 1);
current = "";
}
}
else if (buttn == '.') {
if (current.length() > 0) {
current.remove(current.length() - 1);
lcd.clear();
lcd.setCursor(1, 0);
lcd.print(current);
}
}
else {
current += buttn;
lcd.print(buttn);
}
}
void setup(){
Serial.begin(115200);
lcd.begin(16, 2);
messageScreen();
lcd.clear();
lcd.cursor();
lcd.setCursor(1, 0);
}
void loop() {
updateCursor();
char buttn = keypad.getKey();
if (buttn) {
inputs(buttn);
}
}