IDE warnings

Projects Programming
1

I loaded an example sketch, compiled it and got a load of warnings. (Unused variables, comparisons that will always resolve to false etc)
Without doing anything to the sketch, I compiled it again and got no warnings.

I understand that the warnings are related to one of the libraries, and I suspect if the sketch used other features of the library the warnings about (eg) unused variables might go away.
But what is the significance of getting the warnings on the first compile, but not the second?

2

what is the significance of getting the warnings on the first compile, but not the second?

What did you change between compiling it the first time and the second time ? Did you perhaps turn off compiler warnings ?

Post the code here so that others can compile it

3

The first time you compile the Arduino IDE saves the compiled version of the library code and reuses it on subsequent compiles, so you will only see the warning messages from libraries the first time you compile. This is also the reason that the first compile tends to be slower than subsequent compiles. If you change the board in Tools > Board you will see the warnings again the first time you compile for a different board.

4

Thanks David.

5

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