You already have noticed that there's no such thing as a static Control::Exists() method, and I, personally, have no idea of any "C# findControl stuff". Perhaps someone who knows C# better than I do can tell you about that. But to check whether a given control is present on a given form, you may inspect that form's Controls property. However, which particular criterium of the controls in there you're going to inspect depends on your concrete scenario, that I don't know of course.
Checking for textBox1 == NULL is basically a valid idea, except that (1) in C++/CLI you'd rather need to compare against nullptr instead of NULL (though I, myself, never actually tried to check against NULL in C++/CLI; maybe that even would work given you include a header that defines NULL) and (2) a control variale you created using the IDE named textBox1 would of course be != nullptr since it gets assigned a valid control in the form's InitializeComponent() method.
All the above pertains to checking for the existence of a given control on one given form. Checking whether a given control exists somewhere throughougt your entire app is possible as well, yet considerably more complicated.
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