Table alignment

Question

I'm not an expert with the tabular environment...I have some problems:

1. I got an error "Extra alignment tab has been changed to \cr."
2. I would like to have the professor name completely to the right.

---

 \documentclass[12pt,a4paper,oneside]{book}
 \usepackage{array,booktabs,siunitx}
 \begin{document}
 \noindent
 \begin{tabular}{@{}l@{\hspace{.5em}}l r}
 Students: &                    &Professor: &\\
 Name1     &\textsc{Surname}    &Name       &\textsc{Surname} \\
 Name2     &\textsc{Surname}    &           &       \\
 Name3     &\textsc{Surname}    &           &
 \end{tabular}
 \end{document}

Can somebody help me?

Answer 1

you had only specified 3 columns but had 4 columns of data, I changed to just use three columns but other layouts are possible depending on how you want it to look...

 \documentclass[12pt,a4paper,oneside]{book}
 \usepackage{array,booktabs,siunitx}
 \begin{document}
 \noindent
 \begin{tabular}{@{}l@{\hspace{.5em}}l@{\hspace{2em}} r}
 Students: &                    &Professor: \\
 Name1     &\textsc{Surname}    &Name   \textsc{Surname} \\
 Name2     &\textsc{Surname}    &             \\
 Name3     &\textsc{Surname}    &        
 \end{tabular}
 \end{document}

or the version with a full width table and 4 columns

 \documentclass[12pt,a4paper,oneside]{book}
 \usepackage{array,booktabs,siunitx}
 \begin{document}
 \noindent
 \begin{tabular*}{\textwidth}
{@{}
l@{\hspace{.5em}}l
@{\extracolsep{\fill}}
r@{\extracolsep{0pt}\hspace{.5em}}r
@{}}
 \multicolumn{2}{c}{Students:}&
 \multicolumn{2}{c}{Professor:} \\
 Name1     &\textsc{Surname}    &Name&   \textsc{Surname} \\
 Name2     &\textsc{Surname}    &             \\
 Name3     &\textsc{Surname}    &        
 \end{tabular*}
 \end{document}

Answer 2

And then there's the plain TeX halign solution - whenever I see a complex tabular arrangement I can't help thinking how much simpler Knuth's halign is...

\documentclass{article}
\begin{document}

\noindent\halign{#\hfil\ &\textsc{#}\hfil\qquad&\hfil #\cr
\bf Students \span\omit & \bf Professor\cr
Joe & Bloggs & R.J.~\textsc{Drofnats}\cr
Jane & Doe \cr
Eric & Halfbee \cr
Annie & Other \cr
}

\end{document}