Redis和Memcache还是Redis？(Redis and Memcache or just Redis?)

 这将打印出一个pthread_t的十六进制表示，无论实际是什么： 
 
void fprintPt(FILE *f, pthread_t pt) {
  unsigned char *ptc = (unsigned char*)(void*)(&pt);
  fprintf(f, "0x");
  for (size_t i=0; i<sizeof(pt); i++) {
    fprintf(f, "%02x", (unsigned)(ptc[i]));
  }
}
 
 为了打印每个pthread_t一个小id，可以使用这样的东西（这个时候使用iostreams）： 
 
void printPt(std::ostream &strm, pthread_t pt) {
  static int nextindex = 0;
  static std::map<pthread_t, int> ids;
  if (ids.find(pt) == ids.end()) {
    ids[pt] = nextindex++;
  }
  strm << ids[pt];
}
 
 根据平台和pthread_t的实际表示，可能需要为pthread_t定义一个operator< ，因为std::map需要对元素进行排序： 
 
bool operator<(const pthread_t &left, const pthread_t &right) {
  ...
}

This will print out a hexadecimal representation of a pthread_t, no matter what that actually is:
 
void fprintPt(FILE *f, pthread_t pt) {
  unsigned char *ptc = (unsigned char*)(void*)(&pt);
  fprintf(f, "0x");
  for (size_t i=0; i<sizeof(pt); i++) {
    fprintf(f, "%02x", (unsigned)(ptc[i]));
  }
}
 
To just print a small id for a each pthread_t something like this could be used (this time using iostreams):
 
void printPt(std::ostream &strm, pthread_t pt) {
  static int nextindex = 0;
  static std::map<pthread_t, int> ids;
  if (ids.find(pt) == ids.end()) {
    ids[pt] = nextindex++;
  }
  strm << ids[pt];
}
 
Depending on the platform and the actual representation of pthread_t it might here be necessary to define an operator< for pthread_t, because std::map needs an ordering on the elements:
 
bool operator<(const pthread_t &left, const pthread_t &right) {
  ...
}