c - 替换 Linux 内置的 cmp 实用程序

Question

Linux 的 cmp 命令逐字节比较两个文件，并返回第一个差异(如果现在存在差异，则不返回任何内容)。

在 C 中可以做些什么或其他什么来做到这一点？是否会像比较 getchar 或 fscanf 的两次调用一样简单，一旦发现差异就立即中断 break？

Answer 1

Linux's cmp command compares two files, byte-by-byte ...

经过一些优化:

Get the optimal block size of the files.
Find the rough position of the first difference by reading words, not bytes.

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Would it be as simple as comparing two calls of getchar or maybe fscanf and breaking as soon as a difference is found?

它有一些额外的东西:

   -i, --ignore-initial=SKIP
          skip first SKIP bytes of both inputs

   -i, --ignore-initial=SKIP1:SKIP2
          skip first SKIP1 bytes of FILE1 and first SKIP2 bytes of FILE2

   -n, --bytes=LIMIT
          compare at most LIMIT bytes

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你可以看看 cmp.c [ source code ]