When and Why Use `err.(*os.PathError)` in Go?

Understanding err.(*os.PathError) in Go

In Go's documentation on effective error handling (https://golang.org/doc/effective_go.html#errors), you may have encountered the code snippet:

<code class="go">for try := 0; try <p>This code demonstrates the use of err.(*os.PathError). Let's delve into what it means.</p>
<h3 id="What-is-err-os-PathError">What is err.(*os.PathError)?</h3>
<p>When os.Create is called, it returns an error as its second return value. This error implements the error interface { Error() string }. Any data type that possesses an Error method can implement this interface and be assigned to it.</p>
<p>Typically, simply outputting the error message suffices. However, in the given example, the program aims to handle the ENOSPC (no space left on device) error specifically. The os package provides an *os.PathError as the error implementation in such cases. If you need to access further information about the error, you can cast it.</p>
<h3 id="Type-Assertion-e-ok-err-os-PathError">Type Assertion: e, ok := err.(*os.PathError)</h3>
<p>The statement e, ok := err.(<em>os.PathError) employs type assertion. It verifies if the interface value err holds a </em>os.PathError as its concrete type, and if so, it returns that value. If a different type is present in the interface (other types may also implement the error interface), it simply returns the zero value and false (nil, false in this case).</p></code>

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