How to fix C error 'errno undeclared'
Problem:
You have C code like
errno = EFAULT;
but when you try to compile it you see an error message like
main.c: In function ‘main’:
main.c:4:5: error: ‘errno’ undeclared (first use in this function)
errno = EFAULT;
^~~~~
main.c:4:5: note: each undeclared identifier is reported only once for each function it appears in
main.c:4:13: error: ‘EFAULT’ undeclared (first use in this function)
errno = EFAULT;
Solution
Add
#include <errno.h>
at the top of the source file where the error occured. This will include both the errno
variable and specific error codes like EFAULT
.