#include <pwd.h>

struct passwd * getpwnam(const char * username);

struct passwd * getpwuid(int uid);

struct passwd
{ char *  pw_name;       /* user name */
  char *  pw_passwd;     /* encrypted password */
  uid_t   pw_uid;        /* user uid */
  gid_t   pw_gid;        /* user gid */
  time_t  pw_change;     /* password change time */
  char *  pw_class;      /* user access class */
  char *  pw_gecos;      /* Honeywell login info */
  char *  pw_dir;        /* home directory */
  char *  pw_shell;      /* default shell */
  time_t  pw_expire;     /* account expiration */
  int     pw_fields;     /* internal: fields filled in */ };

(uid_t, gid_t, and time_t are all types of int)