I2C on Leonardo and Uno !

I have , a Leonardo , and an uno , and for a weather station , wanted the two of them to communicate , and decided to go with I2C .
I hooked up them to my laptop , connected ground together , and hooked up the wires as SDA(Leonardo)->SDA(Uno) , and similarly SCL wire too .
then I uploaded Master_reader on my uno , and Slave_sender on my Leonardo , and then ...
nothing happened !
then I did it reverse , then also nothing happened !
help me guys !

I2C communication requires 3 wires, SDA, SCL, and GND.

i connected
Leonardo Uno
respectively !

How long are the SDA, SCL, and GND wires?

Run the Slave code on the Slave and the i2c_scanner on the Master.
The Master should find the Slave.

Perhaps you have a bad cheap clone that doesn't have SDA and SCL connected.