draw with \foreach command

Question

I would like to draw with \foreach command but in below example, the first tikzpicture works fine, the second one doesn't.

But I think the second one should be the same as the first one. Why doesn't it work?

\documentclass[border=10mm]{standalone}
\usepackage{tikz}

\begin{document}
% This one works
\begin{tikzpicture}
\draw[black]  (0,0) \foreach \x/\y in {1/1,1/1.732}  {
    -- (\x,\y)
} -- cycle;
\end{tikzpicture}
% This one doesn't work
\begin{tikzpicture}
\draw[black]  \foreach \x/\y in {0/0,1/1,1/1.732}  {
    (\x,\y) --
} cycle;      
\end{tikzpicture}

\end{document}

Answer 1

\documentclass[border=3mm]{standalone}
\usepackage{tikz}
\begin{document}

% This one works
\begin{tikzpicture}
\draw[black]  (0,0) \foreach \x/\y in {1/1,1/1.732}  {
    -- (\x,\y)
    } -- cycle;
\end{tikzpicture}

% And this also now works
\begin{tikzpicture}
\draw[black] \foreach \x/\y [count=\i]in {1/1, 1/1.732} {%
   \ifnum\i=1(0,0)\else\fi -- (\x,\y)
   } -- cycle;      
\end{tikzpicture}

\end{document}