int scanf(const char *format, ...);
int fscanf(FILE *stream, const char *format, ...);
int sscanf(const char *str, const char *format, ...);
int vscanf(const char *format, va_list ap);
int vfscanf(FILE *stream, const char *format, va_list ap);
int vsscanf(const char *str, const char *format, va_list ap);