示例代码如下：
\documentclass{article}
\usepackage{tikz}
\begin{document}
\def\lastx{10}
\foreach \x[count=\xi from 2,remember=\x as \lastx] in {15,19,20,25} {
This variable \x, the value before was \lastx\space and it is the argument \xi\space in the list.\par}
\end{document}
This variable 15, the value before was 10 and it is the argument 2 in the list.
This variable 19, the value before was 15 and it is the argument 3 in the list.
This variable 20, the value before was 19 and it is the argument 4 in the list.
This variable 25, the value before was 20 and it is the argument 5 in the list.
