Need help changing if else statements into switch case - arduino

Question

So i need help changing the if else statements into switch case statements as i'm new to coding in arduino and can't seem to get it to work. The program is supposed to blink the LED, sound the speaker, light up the bulb, spin the fan and also display the selected message onto the 16x2 lCD when the conditions in the if else statements are fufilled.
#include <LiquidCrystal.h>
//Pins of LCD RS E D4 D5 D6 D7
LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // Pins of Arduino
int tempPin = A0; //LM35 Pin
int ldrPin = A1; //LDR Pin
int led = 6; //LED Pin
int tempMax = 100;
int buzzer = 13;
float temp;
float tempC;
int lightReading;
int numTones = 2;
int tones[] = {440, 349};
int TIP120pin = 5;
int bulb = A2;
void setup()
{
lcd.begin(16, 2);
Serial.begin(9600);
pinMode(led, OUTPUT);
pinMode(tempPin, INPUT);
pinMode(ldrPin, INPUT);
pinMode(buzzer,OUTPUT);
pinMode(TIP120pin, OUTPUT);
pinMode(bulb, OUTPUT);
lcd.clear();
beep(100);
}
void loop()
{
tempC = (5.0 * analogRead(tempPin) * 100.0) / 1024;
temp = tempC;
lightReading = analogRead(ldrPin);
lcd.print("TEMP:");
lcd.setCursor(5, 0);
lcd.print(temp); // display the temperature
lcd.print("C");
// Display Light on second row
lcd.setCursor(0, 1);
lcd.print("Light ");
lcd.setCursor(6, 1);
lcd.print(lightReading);
delay(500);
analogWrite(TIP120pin, 0);
analogWrite(bulb, 0);
if (temp >=35) // if temp is higher than max temp
{
lcd.clear();
analogWrite(TIP120pin, 255);
lcd.setCursor(3, 0);
lcd.print("Room Hot!!");
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
}
else if (temp >=30 && temp<35)
{
lcd.clear();
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Warm!");
delay(200);
}
else if (lightReading >100 && lightReading <= 200)
{
lcd.clear();
analogWrite(bulb, 150);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
// Display Light on second row
lcd.setCursor(3, 0);
lcd.print("Room Dim");
delay(200);
analogWrite(TIP120pin, 0);
}
else if (lightReading <=100)
{
lcd.clear();
analogWrite(bulb, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Dark");
delay(200);
analogWrite(TIP120pin, 0);
}
else if(temp>=35 && lightReading>100 && lightReading<=200)
{
lcd.clear();
analogWrite(bulb, 150);
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Hot!");
lcd.setCursor(3, 1);
lcd.print("Room Dim!");
delay(200);
}
else if(temp>=35 && lightReading<=100)
{
lcd.clear();
analogWrite(bulb, 255);
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Hot!");
lcd.setCursor(3, 1);
lcd.print("Room Dark!");
delay(200);
}
else if(temp>=30 && temp<35 && lightReading>=100 && lightReading <=200)
{
lcd.clear();
analogWrite(bulb, 150);
analogWrite(TIP120pin, 150);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Warm!");
lcd.setCursor(3, 1);
lcd.print("Room Dim!");
delay(200);
}
else if (temp>=30 && temp<35 && lightReading<100)
{
lcd.clear();
analogWrite(bulb, 255);
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Hot!!");
lcd.setCursor(3, 1);
lcd.print("Room Dark!");
delay(200);
}
else
{
digitalWrite(led, LOW);
digitalWrite(buzzer, LOW);
analogWrite(bulb, LOW);
lcd.print("TEMP:");
lcd.setCursor(5, 0);
lcd.print(temp);
lcd.print("C");
// Display Light on second row
lcd.setCursor(0, 1);
lcd.print("Light ");
lcd.setCursor(6, 1);
lcd.print(lightReading);
}
delay(500);
lcd.clear();
Serial.print("Light, "); Serial.print(lightReading); Serial.print('\n');
}
void beep(unsigned char delayms){
for(int x=0; x<numTones; x++)
{
tone(buzzer, tones[x]);
delay(delayms);
}
noTone(buzzer);
}

Answer 1

if you want to convert if statement to Switch ,i.e i am assuming that you want to improve the readability of the code ,you can use if statement in loop and put switch in a function ..check the code below
void loop()
{
tempC = (5.0 * analogRead(tempPin) * 100.0) / 1024;
temp = tempC;
lightReading = analogRead(ldrPin);
lcd.print("TEMP:");
lcd.setCursor(5, 0);
lcd.print(temp); // display the temperature
lcd.print("C");
// Display Light on second row
lcd.setCursor(0, 1);
lcd.print("Light ");
lcd.setCursor(6, 1);
lcd.print(lightReading);
delay(500);
analogWrite(TIP120pin, 0);
analogWrite(bulb, 0);
if (temp >=35) // if temp is higher than max temp
{
doSomething('a');
}
else if (temp >=30 && temp<35)
{
doSomething('b');
}
else if (lightReading >100 && lightReading <= 200)
{
doSomething('c');
}
else if (lightReading <=100)
{
doSomething('d');
}
else if(temp>=35 && lightReading>100 && lightReading<=200)
{
doSomething('e');
}
else if(temp>=35 && lightReading<=100)
{
doSomething('f');
}
else if(temp>=30 && temp<35 && lightReading>=100 && lightReading <=200)
{
doSomething('g');
}
else if (temp>=30 && temp<35 && lightReading<100)
{
doSomething('h');
}
else
{
doSomething('i');
}
and put your different condition in the switch statement in the doSomething() function like this
void doSomething(condition){
switch(condition){
case 'a' : // if temp is higher than max temp
lcd.clear();
analogWrite(TIP120pin, 255);
lcd.setCursor(3, 0);
lcd.print("Room Hot!!");
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
break;
case 'b' :
lcd.clear();
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Warm!");
delay(200);
break;
case 'c' :
lcd.clear();
analogWrite(bulb, 150);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
// Display Light on second row
lcd.setCursor(3, 0);
lcd.print("Room Dim");
delay(200);
analogWrite(TIP120pin, 0);
break;
case 'd':
lcd.clear();
analogWrite(bulb, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Dark");
delay(200);
analogWrite(TIP120pin, 0);
break;
case 'e':
lcd.clear();
analogWrite(bulb, 150);
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Hot!");
lcd.setCursor(3, 1);
lcd.print("Room Dim!");
delay(200);
break;
case 'f':
lcd.clear();
analogWrite(bulb, 255);
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Hot!");
lcd.setCursor(3, 1);
lcd.print("Room Dark!");
delay(200);
break;
case 'g':
lcd.clear();
analogWrite(bulb, 150);
analogWrite(TIP120pin, 150);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Warm!");
lcd.setCursor(3, 1);
lcd.print("Room Dim!");
delay(200);
break;
case 'h':
lcd.clear();
analogWrite(bulb, 255);
analogWrite(TIP120pin, 255);
digitalWrite(led, HIGH);
delay(200);
beep(50);
digitalWrite(led, LOW);
delay(200);
lcd.setCursor(3, 0);
lcd.print("Room Hot!!");
lcd.setCursor(3, 1);
lcd.print("Room Dark!");
delay(200);
break;
default:
digitalWrite(led, LOW);
digitalWrite(buzzer, LOW);
analogWrite(bulb, LOW);
lcd.print("TEMP:");
lcd.setCursor(5, 0);
lcd.print(temp);
lcd.print("C");
// Display Light on second row
lcd.setCursor(0, 1);
lcd.print("Light ");
lcd.setCursor(6, 1);
lcd.print(lightReading);
break;
}
}

Answer 2

In Java, the switch statement takes this form:
switch (expression)
{
case constant:
statements;
break;
[ case constant-2:
statements;
break; ] ...
[ default:
statements;
break; ] ...
}
The switch statement works with the byte, short, char, and int primitive data types. It also works with enumerated types, the String class, and a few special classes that wrap certain primitive types: Character, Byte, Short, and Integer.
Your nested ifs with their boolean expressions are not a good fit for switch.