main used in CS162
* asterisk
& ampersand
don’t use and, or, xor in C!!
not native boolean support
#include<stdbool.h>
#include <stdint.h>
uint8_t
off_t: file offsets, signed
pid_t: process IDs, signed
pthread_t: to identify a thread, unsigned
size_t: sizes of objects, unsigned
ssize_t: size_t and also -1 for error
char *a="lalala"; // in static, inmutable, forbidden from C++11
char b[]="lalala"; // in stack if local, static if global
strcmp, strcat.. with assumption of proper string better not safe
strncat, strncpy.. with length argument are better