calling-c: elaborate on the x_dpy example

The following code is not valid Pony code let x_dpy = @XOpenDisplay(Pointer[U8])
ponylang · Dec 29, 2023 · 39d72a3 · 39d72a3
1 parent ad98266
commit 39d72a3
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/docs/c-ffi/calling-c.md b/docs/c-ffi/calling-c.md
@@ -80,7 +80,8 @@ use @eglGetDisplay[Pointer[_EGLDisplayHandle]](disp: Pointer[_XDisplayHandle])
 primitive _XDisplayHandle
 primitive _EGLDisplayHandle
 
-let x_dpy = @XOpenDisplay(Pointer[U8])
+let x_dpy_name: String = // ...
+let x_dpy = @XOpenDisplay(x_dpy_name.cstring())
 if x_dpy.is_null() then
   env.out.print("XOpenDisplay failed")
 end