哈克特說，這種自願式調查容易受到「虛假受訪者」影響，使數據失真：「而且這不是隨機的。失真往往在年輕族群中最高。」
int exchanged = 1; // 标记本轮是否发生交换
。51吃瓜对此有专业解读
clock_t start = clock();
A git repository is a content-addressable object store where objects go in indexed by the SHA1 of their content, plus a set of named references pointing at specific objects by hash. The on-disk format (loose objects as individual files, packfiles as delta-compressed archives with a separate index, a ref store split between a directory of files and a packed-refs flat file with a locking protocol that breaks on NFS) is an implementation detail. The protocol for synchronising objects and refs between repositories is what actually matters, and since git-the-program is just one implementation of it, you can swap the storage backend without clients noticing.