\documentclass{article}% Jean-Côme Charpentier
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{listings}
\usepackage[svgnames]{xcolor}

\newcommand*\bkgcolor[1]{%
  \fboxsep=0pt
  \fboxrule=0pt
  \fcolorbox{DarkBlue}
            {DarkBlue}
            {\textcolor{white}{\bfseries\strut#1}}%
}

\lstset{language=C, keywordstyle=\bkgcolor,
  morekeywords={PROCESS,Process}}

\begin{document}
\begin{lstlisting}
int main(int argc, char** argv){
  printf("hello world!\n");
  PROCESS;
  Process;
  return 0;
}
\end{lstlisting}
\end{document}