Inputing data for a tabular environment leads to a weird extra space [duplicate]

Question

I'm writing a table and I'm trying to import its contents from an external file. Curiously, I found out that when importing the contents TeX seems to add a weird space to the last entry. This does not occur when I copy the contents from the external file and paste them directly on the document. How can I fix this behavior?

MWE:

\documentclass[margin=0.1cm]{standalone}

\begin{filecontents*}{data.tex}
01 & 02 & 03 & 04 & 05\\06 & 07 & 08 & 09 & 10\\11 & 12 & 13 & 14 & 15\\16 & 17 & 18 & 19 & 20\\21 & 22 & 23 & 24 & 25
\end{filecontents*}

\begin{document}

\begin{tabular}{c|c|c|c|c}
\input{data.tex}
\end{tabular}

\begin{tabular}{c|c|c|c|c}
01 & 02 & 03 & 04 & 05\\06 & 07 & 08 & 09 & 10\\11 & 12 & 13 & 14 & 15\\16 & 17 & 18 & 19 & 20\\21 & 22 & 23 & 24 & 25
\end{tabular}

\end{document}

The result of the MWE is shown below. The left table is inputted, and the right one is typed directly. Notice how 25 has different alignments in each case.

Answer 1

This happens due to the handling of \input{…} (with LaTeX from 2020-10-01 AFAIK there is even extra hook code after the end of an \input) and because, you have an extra space token: the end of line after \input{…}. To avoid this, comment the end of line after \input{…}:

\documentclass[margin=0.1cm]{standalone}

\begin{filecontents*}{data.tex}
01 & 02 & 03 & 04 & 05\\06 & 07 & 08 & 09 & 10\\11 & 12 & 13 & 14 & 15\\16 & 17 & 18 & 19 & 20\\21 & 22 & 23 & 24 & 25
\end{filecontents*}

\begin{document}

\begin{tabular}{c|c|c|c|c}
\input{data.tex}% <-- this percent is needed
\end{tabular}

\begin{tabular}{c|c|c|c|c}
01 & 02 & 03 & 04 & 05\\06 & 07 & 08 & 09 & 10\\11 & 12 & 13 & 14 & 15\\16 & 17 & 18 & 19 & 20\\21 & 22 & 23 & 24 & 25
\end{tabular}

\end{document}

Note: This would not happen with plainTeX's \input …, because in this case the space token (of the end-of-line) would be the end of the filename. But this would, e.g., not support filenames with spaces.

See also: What is the use of percent signs (%) at the end of lines? (Why is my macro creating extra sp...