compare char receive from Slave writer to Master reader with I2C
Improve you indentation.
If you want to compare two strings use strcmp function for that.
Your master part has some brackets left in your void loop() function, correct them.
In I2C you are receiving one byte at time. You should receive data till the last byte in received.
You should have some identification in your message, which is you are sending from slave to master indicating that this is last character. It helps you come out of Data reception loop in Master side.