【不懂】什么是抛出的不同的异常？

#ifndef H***E_VASPRINTF
int vasprintf (char **, const char *, va_list);
#endif

#ifdef __USE_GNU
/* Write formatted output to a string dynamically allocated with `malloc'.
   Store the address of the string in *PTR.  */
extern int vasprintf (char **__restrict __ptr, __const char *__restrict __f,
		      __gnuc_va_list __arg)
     __THROW __attribute__ ((__format__ (__printf__, 2, 0))) __wur;