How to fix C error 'unknown type name va_list'

Problem:

You have C code like

main.c

va_list ap;
int mode = va_arg(ap, int);

va_list ap;
int mode = va_arg(ap, int);

but when you try to compile it you see a warning message like

error_message.txt

main.c: In function ‘main’:
main.c:4:2: error: unknown type name ‘va_list’
  va_list ap;
  ^~~~~~~

main.c: In function ‘main’:
main.c:4:2: error: unknown type name ‘va_list’
  va_list ap;
  ^~~~~~~

Add

stdarg_include.c

#include <stdarg.h>

#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.

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