/newcommand{/tabincell}[2]{/begin{tabular}{@{}#1@{}}#2/end{tabular}}%放在导言区
%然后使用&/tabincell{c}{}&就可以在表格中自动换行

%比如这么用
/begin{tabular}{|c|c|}
/hline
1 & the first line //
/hline
2 & /tabincell{c}{haha// heihei//zeze} //
/hline
/end{tabular}

以下为一例子，可直接存为.tex文件编译运行:

\documentclass[a4paper,12pt]{article}
\begin{document}
\begin{table}
\newcommand{\tabincell}[2]{\begin{tabular}{@{}#1@{}}#2\end{tabular}}
  \centering
  \begin{tabular}{|c|c|c|}\hline
1 & \tabincell{c}{the first line \\ the next\\the next\\ last} & \tabincell{c}{one \\ one}\\\hline
2 & \tabincell{c}{hello\\ aha\\ ok \\yes \\en} & \tabincell{c}{two \\ two \\ two} \\\hline
\end{tabular}
  \caption{longtitle}
\end{table}

\end{document}

结果如下图：