C#- Help with code

Hello, I just need some quick help here:

Code:

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this.Controls[string.Format("S" + S)].Show();

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Code:

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this.Controls[string.Format("S" + S)].Visible = true;

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None of these works. I have controls called S0-S10(LineShapes). The S variable is currently 0. I get a NullReferenceException error during runtime.

Note: tried it with a button aswell.

Edit: It's for a hangman game, S0-S10 are lines and a sphere.

Thanks, I hope it's just something easy.

What exactly is the string.Format call for? There's no formatting going on. If you were to use string.Format it would look like this:

Code:

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this.Controls[string.Format("S{0}", S)].Show();

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but that's pointless with so simple a string, so just do this:

Code:

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this.Controls["S" + S].Show();

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Thanks!