Not receiving values from master to the slave

Projects General Guidance
1

Hello,
I am trying to store two values in master via serial monitor and after storing those values i am sending to the slave where i have to perform arithmatic operations between these two values and result will be sent back to the master.My question is I am sending values from master but slave is not receiving the value so please help me out for this query.I am attaching code below.
thanks in advance.

//Master................................................................................
#include <Wire.h>
int a;
int b;
int c;
int d;
void setup(){

Serial.begin(9600);
delay(100);
Serial.println("\n Please enter the values for Operations"); // enter values of a and b via serial Monitor
}
void loop(){
a = 0; // a initiated with 0 first
while(Serial.available() == 0){}
while(Serial.available()){
  byte incoming = Serial.read();
  a = incoming - '0';

  Serial.print("a = ");
  Serial.println(a); 
  delay(1000);
int c = a; // store value of a in c
Serial.print("Now the value in c is =  ");
  Serial.println(c); 
}
b = 0;
while(Serial.available() == 0){}
while(Serial.available()){
  byte incoming = Serial.read();
  b = incoming - '0';

  Serial.print("b = ");
  Serial.println(b);
  
  byte d = b;
  Serial.print("Now the value in d is = ");
  Serial.println(d);

delay(5000);
}

Wire.beginTransmission(1); // begin transmission to slave1
Wire.write("c is ");
Wire.write(c); // sending value of c

Wire.write("d is ");

Wire.write(d);// sending value of d
Wire.endTransmission();
delay(500);
}

Slave.........................................................................
#include <Wire.h>
void setup() {
Wire.begin(1);// slave address is 1
Wire.onReceive(recieveEvent);
Serial.begin(9600);

}

void loop() {
delay(100);

}
void recieveEvent(int howMany){
while(1 < Wire.available()){
  char e = Wire.read();
  Serial.print(e);
//  char f = Wire.read();
 // Serial.print(f);
  
}
int c = Wire.read();// read data from master
Serial.println(c);
//int b = Wire.read();// read data from master
//Serial.println(b);

}
2

Please read the "How to use the forum-please read" stickies to see how to format (Ctrl-T) and post code properly.

Start with the serial input basics thread to see how to receive multi digit numbers.

3 
int c = a; // store value of a in c

Now, you have two variables named c - one at global scope and one at local scope.

}

Now, the local one went out of scope (ceased to exist), and the global one has not been re-valued.

 byte d = b;
  Serial.print("Now the value in d is = ");
  Serial.println(d);

delay(5000);
}

Same problem. The global d is not re-valued.

Why is the local c an int, while the local d is a byte?

Wire.beginTransmission(1); // begin transmission to slave1
Wire.write("c is ");
Wire.write(c); // sending value of c

Wire.write("d is ");

Wire.write(d);// sending value of d
Wire.endTransmission();

You are sending "c is 0d is 0". Is that useful information from the slave's point of view?

Wouldn't sending just the two bytes make more sense?

void recieveEvent(int howMany){
while(1 < Wire.available()){
  char e = Wire.read();
  Serial.print(e);
 
}
int c = Wire.read();// read data from master
Serial.println(c);

}

After snipping the comments, this is your code on the slave to read the incoming data (remember, it is "c is 0d is 0").

What ends up in the char e?
What ends up in the int c?

Why are the two variables different types?

Why does the slave never compute a result?

Why does the slave never send a reply?
Why does the master never read the reply (that the slave didn't send)?

Why are you abusing I2C this way?

Sorry about more questions than answers, but, perhaps in the process of answering the questions, you'll realize what is wrong.