这都是啥
什么是抛出的不同的异常?
#ifndef HAVE_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;