Problem:
You have C code like
va_list ap; int mode = va_arg(ap, int);
but when you try to compile it you see a warning message like
main.c: In function ‘main’: main.c:4:2: error: unknown type name ‘va_list’ va_list ap; ^~~~~~~
Solution:
Add
#include <stdarg.h>
at the top of the source file where the error occured. This will include the definitions for va_list
and the va_arg
function.