L1 is not declared in this scope error

Question

I have a project where I have to control a DC motor. In this code the purpose is that every time you press a button the direction of the motor changes.

I only get the error that L1 (and L2,R1 and R2) are not declared in this scope. the place in the loop. How do I define the variables so that the code works?

int Motorforward = 10; // MotorDirectionPin set to pin10
int Motorbackward = 11; // MotorDirectionPin set to pin11
const int button1Pin = 2; //button control set to pin 2
int state = L1;
int state = L2;
int state = R1;
int state = R2;
int button1State; // current reading from the input pin
int previous = LOW; //the previous reading from the input pin
char input;
void setup(){
pinMode(button1Pin, INPUT); //set pin as input
Serial.begin(9600);
pinMode(Motorforward, OUTPUT); // sets the pin as output
pinMode(Motorbackward, OUTPUT);
 }
 void loop(){
button1State = digitalRead(button1Pin);
input = button1State;
switch(state){
 case L1:
 if (state == L1){
 if (button1State == HIGH){
 state == L2;
 }
 }
 break;
case L2:
 if (state == L2){
 if (button1State == LOW){
 state == R1;
 }
 }
 break;
case R1:
 if (state == R1){
 if (button1State == HIGH){
 state == R2;
 }
 }
 break;
case R2:
 if (state == R2){
 if (button1State == LOW){
 state == L1;
 }
 }
 break;
}

• Majenko: How many state variables do you want?! And it is quite correct. At no point do you ever declare those symbols.
• Annelouk van Mierlo: Do you mean the different states the motor can be in? in that case 4 states in which case 1 and 2 and case 3 and 4 give the same result.
• Majenko: No, I mean how many state variables do you want? You define the same variable 4 times, each time with a different assignment, and an assignment to a variable or macro that you haven't defined at that.

Answer 1

I have the feeling you need only one state which can have 4 values: L1, L2, R1 or R2.

For this, use an enum:

enum EState { L1, L2, R1, R2 };

Now create one state variable of that type and give it an initial value.

EState state = L1;

Some other problems I see at first sight:

case L1:
 if (state == L1){
 if (button1State == HIGH){
 state == L2;
 }
}
break;

In this statement, when there is case L1, it means the code following ( until the break) is only handled when the state (because of switch(state) is L1, so you can remove the check if (state == L1). What is left is:

case L1:
 if (button1State == HIGH)
 {
 state == L2;
 }
 break;

Than you use state == L2 to set a new state. However, the == only compares two values, if you want to assign it, you have to use a single =, thus the code should be:

case L1:
 if (button1State == HIGH)
 {
 state = L2;
 }
 break;

Of course you have to do this also for the other case statements.

Tip: align your code (make the { and } aligned under each other; this will make your code readability much better.

Answer 2

You have not defined L1, L2, R1, or R2. You're also redefining the int variable 'state' four times.

Try replacing:

int state = L1;
int state = L2;
int state = R1;
int state = R2;

With something like:

#define L1 1
#define L2 2
#define R1 3
#define R2 4
int state = R2;