c – Incompatible implicit declaration of built-in function ‘malloc’

c – Incompatible implicit declaration of built-in function ‘malloc’

You likely forgot to #include <stdlib.h>

You need to #include <stdlib.h>. Otherwise its defined as int malloc() which is incompatible with the built-in type void *malloc(size_t).

c – Incompatible implicit declaration of built-in function ‘malloc’

Youre missing #include <stdlib.h>.