Runaway argument?
! Forbidden control sequence found while scanning use of lst@next.
<inserted text>
                par
l.23 codeListing{x <- y}{f(g(x))}

documentclass[english]{article}
usepackage[latin9]{inputenc}
usepackage{geometry}
begin{document}

newcommand{codeListing}[2]{
begin{tabular}{p{8cm} p{8cm}}
begin{lstlisting}
#1
end{lstlisting}
&
#2tabularnewline
end{tabular}
}

section{verbatim test}
begin{verbatim}
logLik <- function(x) {
  y <<- x^2+2
  return(sum(sqrt(y+7)))
}
end{verbatim}

section{codeListing test}
codeListing{}{
logLik <- function(x) {

~~y <<- x^2+2

~~return(sum(sqrt(y+7)))

}

}

end{document}

documentclass{article}
usepackage{xparse}
ExplSyntaxOn
NewDocumentCommand {codeListing} { O{} +v O{} +v }
  {
    begin{table}[h]centering
      begin{tabular}[width=textwidth]{ll}
        newlinechar=endlinechar
        exp_args:Nx scantokens
          {
            stringbegin{lstlisting}[unexpanded{#1}]
              #2
            stringend{lstlisting}
            &
            stringbegin{lstlisting}[unexpanded{#3}]
              #4
            stringend{lstlisting}
          }
      end{tabular}
    end{table}
  }
ExplSyntaxOff
usepackage[a4paper,margin=2cm]{geometry}
usepackage{listings}
usepackage{xcolor}
usepackage{lipsum}
begin{document}
lipsum[1]

codeListing[language=C,backgroundcolor=color{yellow!30}]$
#include <stdio.h>

int main(void)
{
  printf("Hello worldn");
  return 0;
}
$[language=C++,backgroundcolor=color{red!20}]$
#include <iostream>

using namespace std;
int main()
{
  cout << "Hello World!" << endl;
  return 0;
}
$

lipsum[2]

end{document}

documentclass{article}
usepackage[a4paper,margin=2cm]{geometry}
usepackage{listings}

lstnewenvironment{K}{lstset{language=C}}{}
lstnewenvironment{M}{lstset{language=C++}}{}
newenvironment{T}{begin{table}[h]centeringbegin{tabular}[width=textwidth]{ll}}{end{tabular}end{table}}

usepackage{lipsum}
begin{document}
lipsum[1]

begin{T} begin{K}
#include <stdio.h>

int main(void)
{
  printf("Hello worldn");
  return 0;
}
end{K} & begin{M}
#include <iostream>

using namespace std;
int main()
{
  cout << "Hello World!" << endl;
  return 0;
}
end{M} end{T}

lipsum[2]

end{document}

codeListing{$e^i$}{}

codeListing{%}{}
codeListing{}}{}

verb~%~
verb~}~

documentclass{article}
usepackage[a4paper,margin=2cm]{geometry}
usepackage[table,cmyk,dvipsnames]{xcolor}
usepackage{array,longtable}

arrayrulewidth=fboxrule
tabcolsep=2fboxsep
arrayrulecolor{white}


newcolumntype{A}[2]{%
    >{begin{minipage}{%
        dimexpr#2linewidth-2tabcolsep-#1arrayrulewidthrelax}%
        vspacetabcolsep}c<{vspacetabcolsep
    end{minipage}}}

usepackage{listings}
lstset
{
    language=[Sharp]C,
    breaklines=true,
    breakindent=0pt,
    tabsize=3,
    aboveskip=0dimexprfboxsep+fboxrulerelax,
    belowskip=-dimexprfboxsep+fboxrulerelax,
    frame=single,
    framesep=fboxsep,
    framerule=fboxrule,
    rulecolor=color{Yellow!30},
    xleftmargin=0dimexprfboxsep+fboxrulerelax,
    xrightmargin=dimexprfboxsep+fboxrulerelax,
    showstringspaces=false,
    basicstyle=color{Maroon}scriptsizett,
    keywordstyle=color{Blue}sfbf,
    commentstyle=color{Cyan},
    stringstyle=color{Green},
    backgroundcolor=color{Yellow!30}
}


usepackage{lipsum}
begin{document}
lipsum[1]
begin{longtable}{*2{|A{1.5}{0.45}}|}hline
lstinputlisting{SourceCode.cs}&lstinputlisting{SourceCode.cs}tabularnewlinehline
lstinputlisting{SourceCode.cs}&lstinputlisting{SourceCode.cs}tabularnewlinehline
end{longtable}
lipsum[2]
end{document}

newwritetempfile

newcommand{example}[1]{
    immediateopenouttempfile=jobname.tmp
    immediatewritetempfile{#1}
    immediatecloseouttempfile
    input{jobname.tmp}
    lstinputlisting{jobname.tmp}
}

example{unexpanded{lipsum[1]}}