\documentclass[]{article}
\usepackage{xcolor,listings}

\begin{document}

\lstset{
    language=C,
    keywordstyle=\color{blue},
    numbers=left,
}

\begin{lstlisting}
    signed main(const int argc, const char * argv[]) {
        // This is a bridge
        return 0;
    }
\end{lstlisting}

\end{document}