Implicit declaration of function is invalid in c99 keil July 8, 2019 16 32 64 128 Implicit declaration of function 'fork' is invalid in c99 -werror -wimplicit-function-declaration Implicit declaration of function 'f' is invalid in c99 -werror -wimplicit-function-declaration Implicit declaration of function 'kbhit' is invalid in c99
