Please consider the following MWE:
\documentclass{article}
\usepackage{siunitx, etoolbox}
\newcommand{\testa}{Some text}
\newcommand{\testb}{40}
\begin{document}
\begin{itemize}
\item Item 1
% \ifnotnull{\testa}{\item This appears only if testa is not null}{\item Oh! testa is null}
\ifnumgreater{\testb}{49}{\item This appears only if testb is greater than 49}{\item Oh! testb is lesser than 49}
\end{itemize}
\end{document}
What command do I use in place of \ifnotnull to check if \testa is/ is not null?
\ifnumequal{0\test}{0}...– Ulrike Fischer Feb 02 '15 at 10:53etoolbox, hint\ifblankcannot test on macros. But is nice to test if say#1is empty – daleif Feb 02 '15 at 11:17\ifdefstring{\testa}{}..– Ulrike Fischer Feb 02 '15 at 11:28