It took me a while to figure out while I had this error when compiling my Arduino sketch. My project was spread on several files I created. My class was actually defined in a header file (mb8877.h), class mb8877 { ... }; but some functions belonging to the class were defined in another file (mb8877.c) such as: void mb8877::decode_command() { ... } That was my mistake! The rule is: if your define functions belonging to a class outside the header file, the file declaring them should bear a .cpp extension. Simply renaming mb8877.c to mb8877.cpp cleared the error.
Parce que j'aime bien la musique. Parce que je trouve bien les instruments. Parce qu'il y a beaucoup de boutons. Et que j'aimerais bien jouer du piano.