Help with the code of data transmission between two arduinos (I2C)

Sorry, we are both right. The gcc compiler that the Arduino uses accepts "0B" for the prefix, and "B" does not work... except that, through Arduino.h, all of the 8-bit values have already been defined through macros that use the "B" prefix. Your code is OK as it stands because of this.

However, I think that if you want to use an int or a long (with a negative sign or larger than 255) then you will have to use the "0B" prefix.

I do not understand your second paragraph at all but I will wait until some code gets posted.