# Table error: Missing number treated as zero

When making a table in Latex with "tabular", I always get the following errors:

• "Missing number, treated as zero \begin{tabular}"
• "Illegal unit of measure (pt inserted) \begin{tabular}"

This is the table:

\\
\begin{table}[h!]
\centering
\renewcommand{\arraystretch}{1.5}
\caption{xx}
\footnotesize
\textwidth
\begin{tabular}{|c||c|c|c|c|c|c|}
\hline
\textbf{1}   & \textbf{1}        & \textbf{3}     & \4       & 5      & 6      & 7       \\ \hline \hline
a        & b             & c              & d              & e             & f             & g              \\ \hline
\end{tabular}
\end{table}