open

The open function can be used to open a file in read-only mode.

A File owns a resource, the file descriptor and takes care of closing the file when it is droped.

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Here's the expected successful output:

$ echo "Hello World!" > hello.txt
$ rustc open.rs && ./open
hello.txt contains:
Hello World!

(You are encouraged to test the previous example under different failure conditions: hello.txt doesn't exist, or hello.txt is not readable, etc.)