Decimal to Hexadecimal Converter

1/*
2 
3  This sketch converts a Decimal number into a Hexadecimal  number.
4  The Decimal number is fed to the Arduino through a 4x4 Keypad.
5  A function then converts this Decimal number to its Hexadecimal
6  equivalent.  These numbers are displayed on a Liquid Crystal Display
7  and Serial Monitor.
8  
9  This program is made by Shreyas for Electronics Champ YouTube Channel.
10  Please subscribe to this channel. Thank You.
11 
12*/
13 
14// including the  libraries
15#include <LiquidCrystal_I2C.h>
16#include <Keypad.h>
17#include <Wire.h>
18  
19// initialize the variables
20const byte ROWS = 4;  //Four rows of Keypad
21const  byte COLS = 4;  //Four columns of Keypad
22char key;
23String decimalNum;
24long  decimalNumber;
25String hexNumber;
26 
27//Define the symbols on the buttons  of the keypad
28char Keys[ROWS][COLS] = {
29 
30  {'1', '2', '3', 'A'},
31  {'4',  '5', '6', 'B'},
32  {'7', '8', '9', 'C'},
33  {'*', '0', '#', 'D'}
34 
35};
36  
37byte rowPins[ROWS] = {2, 3, 4, 5};
38byte colPins[COLS] = {6, 7, 8, 9};
39  
40// create keypad and LCD objects
41Keypad myKeypad = Keypad(makeKeymap(Keys),  rowPins, colPins, ROWS, COLS);
42LiquidCrystal_I2C lcd(0x27, 16, 2);
43 
44void  setup() {
45 
46  // start Serial communication
47  Serial.begin(9600);
48  Serial.println("Electronics  Champ");
49 
50  // initialize the lcd
51  lcd.init();
52  lcd.begin(16, 2);
53  lcd.clear();
54  lcd.backlight();
55  lcd.setCursor(0, 0);
56  lcd.print("Electronics");
57  lcd.setCursor(0, 1);
58  lcd.print("Champ");
59  delay(3000);
60  lcd.clear();
61  lcd.setCursor(0, 0);
62  lcd.print("D: ");
63  lcd.setCursor(3, 0);
64  lcd.print(0);
65  lcd.setCursor(0, 1);
66  lcd.print("H: ");
67  lcd.setCursor(3, 1);
68  lcd.print(0);
69  
70}
71 
72void loop() {
73 
74  key = myKeypad.getKey();
75 
76  if (key)  {
77 
78    if (key != 'A' and key != 'B' and key != 'C' and key != 'D' and key  != '*' and key != '#') {
79 
80      decimalNum = decimalNum + String(key);
81      decimalNumber = decimalNum.toInt();
82 
83      //Converts Decimal to Hexadecimal
84      hexNumber = convertDecimalToHex(decimalNumber);
85 
86      //Prints the  Decimal and the Hexadecimal numbers on the Display
87      lcd.clear();
88      lcd.setCursor(0,  0);
89      lcd.print("D: ");
90      lcd.setCursor(3, 0);
91      lcd.print(decimalNumber);
92      lcd.setCursor(0, 1);
93      lcd.print("H: ");
94      lcd.setCursor(3,  1);
95      lcd.print(hexNumber);
96 
97      //Prints the Decimal number on  the Serial Monitor
98      Serial.print("Decimal: ");
99      Serial.print(decimalNumber);
100      Serial.print("      ");
101 
102      //Prints the Hexadecimal number on  the Serial Monitor
103      Serial.print("Hexadecimal: ");
104      Serial.println(hexNumber);
105  
106    }
107 
108  }
109 
110  //Clears the numbers
111  if (key == 'C') {
112  
113    decimalNum = "";
114    decimalNumber = 0;
115    hexNumber = "0";
116    lcd.clear();
117    lcd.setCursor(0, 0);
118    lcd.print("D: ");
119    lcd.setCursor(3,  0);
120    lcd.print(decimalNumber);
121    lcd.setCursor(0, 1);
122    lcd.print("H:  ");
123    lcd.setCursor(3, 1);
124    lcd.print(hexNumber);
125 
126  }
127 
128}
129  
130//This function converts a Decimal number to a Hexadecimal number
131String  convertDecimalToHex(long n) {
132 
133  String hexNum;
134  long remainder;
135  
136  while (n > 0) {
137 
138    remainder = n % 16;
139    n = n / 16;
140 
141    if (remainder < 10) {
142      hexNum = String(remainder) + hexNum;
143    }
144  
145    else {
146     
147      switch (remainder) {
148     
149        case 10:
150          hexNum = "A" + hexNum;
151          break;
152 
153        case 11:
154          hexNum = "B" + hexNum;
155          break;
156 
157        case 12:
158          hexNum = "C" + hexNum;
159          break;
160 
161        case 13:
162          hexNum = "D" + hexNum;
163          break;
164 
165        case 14:
166          hexNum = "E" + hexNum;
167          break;
168 
169        case 15:
170          hexNum = "F" + hexNum;
171          break;
172 
173      }
174 
175    }
176 
177  }
178 
179  return hexNum;
180 
181}
182