# 6.7 `cmp` -- File comparisons

The `cmp` module defines a function to compare files, taking all sort of short-cuts to make it a highly efficient operation.

The `cmp` module defines the following function:

`cmp` (f1, f2)
  Compare two files given as names. The following tricks are used to optimize the comparisons:

  - Files with identical type, size and mtime are assumed equal.
  - Files with different type or size are never equal.
  - The module only compares files it already compared if their signature (type, size and mtime) changed.
  - No external programs are called.

Example:

      >>> import cmp
      >>> cmp.cmp('libundoc.tex', 'libundoc.tex')
      1
      >>> cmp.cmp('libundoc.tex', 'lib.tex')
      0