printf你会吗？:-)

https://cplusplus.com/reference/cstdio/printf

A format specifier follows this prototype: %[flags][width][.precision][length]specifier

p Pointer address b8000000

n Nothing printed. The corresponding argument must be a pointer to a signed int. The number of characters written so far is stored in the pointed location.

# Used with o, x or X specifiers the value is preceeded with 0, 0x or 0X respectively for values different than zero.Used with a, A, e, E, f, F, g or G it forces the written output to contain a decimal point even if no more digits follow. By default, if no digits follow, no decimal point is written.

* The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

.number For g and G specifiers: This is the maximum number of significant digits to be printed.

.* The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

ll long long int unsigned long long int

int vsnprintf (char * s, size_t n, const char * format, va_list arg ); Write formatted data from variable argument list to sized buffer

int vfscanf ( FILE * stream, const char * format, va_list arg ); Read formatted data from stream into variable argument list

v应该是variable的意思, f:file s:string n:n个 f:format