// #include <stdio.h>
	// #include <stdlib.h>
	//
	// static void myprint(char* s) {
	//   printf("%s\n", s);
	// }
	import "C"
	import "unsafe"

	func main() {
		cs := C.CString("Hello from stdio")
		C.myprint(cs)
		C.free(unsafe.Pointer(cs))
	}

A few special functions convert between Go and C types
by making copies of the data. In pseudo-Go definitions:

	// Go string to C string

The [SliceAt(typ Type, p unsafe.Pointer, len int)] function
returns a Value representing a slice whose underlying array starts

ExpressionStmt = Expression .
</pre>

<p>
The following built-in functions are not permitted in statement context:
</p>

<pre>
append cap complex imag len make new real
unsafe.Add unsafe.Alignof unsafe.Offsetof unsafe.Sizeof unsafe.Slice
</pre>

<pre>
h(x+y)
f.Close()
&lt;-ch
(&lt;-ch)
len("foo")  // illegal if len is the built-in function
</pre>

	w := &Walker{
		context:  context,
		root:     root,
		features: map[string]bool{},
		imported: map[string]*apiPackage{"unsafe": &apiPackage{Package: types.Unsafe}},
	}
	w.loadImports()
	return w
}

func (w *Walker) Features() (fs []string) {
	for f := range w.features {
		fs = append(fs, f)
	}
	sort.Strings(fs)
	return
}

</pre>

<p>
The following built-in functions are not permitted in statement context:
</p>

<pre>
append cap complex imag len make new real
unsafe.Add unsafe.Alignof unsafe.Offsetof unsafe.Sizeof unsafe.Slice unsafe.SliceData unsafe.String unsafe.StringData
</pre>

<pre>
h(x+y)
f.Close()
&lt;-ch
(&lt;-ch)
len("foo")  // illegal if len is the built-in function
</pre>

pkg reflect, func SliceAt(Type, unsafe.Pointer, int) Value #61308...

<code>l.TryLock</code> (or <code>l.TryRLock</code>)
may be considered to be able to return false
even when the mutex <i>l</i> is unlocked.
</p>

<h3 id="once">Once</h3>

<p>
The <code>sync</code> package provides a safe mechanism for
initialization in the presence of multiple goroutines
through the use of the <code>Once</code> type.
Multiple threads can execute <code>once.Do(f)</code> for a particular <code>f</code>,