Highlight commands inside lstlisting algorithm

Question

I'm writing an algorithm with lstlisting

This is the output

And this is the code:

\begin{figure}
\begin{lstlisting}[mathescape=true]
INPUT: Insieme $C$ di cubi che coprono una funzione $f$
OUTPUT: Insieme $D$ di cubi disgiunti che coprono $f$

$D = \emptyset$
while($C \neq \emptyset$):
    BUILD-SOP($C$, $P$) # crea SOP e la inserisce in $P$
    $A\ = \{d\in P\ |\ \forall c \in P \backslash \{d\} : d \cap c = \emptyset \}$
    $D = D \cup A$
    $P = P \backslash A$
    WEIGHT($P$)
    SORP($P$)
    $B = \emptyset$
    while($P\neq \emptyset$):
        $p = P[0]$
        $P = P \backslash \{p\}$
        $D = D \cup \{p\}$
        forall $q \in P\ :\ p \cap q = \emptyset$:
            $P = P \backslash \{q\}$
            BREAK($q$,$p$,$Q$)
            OPT($q$,$Q$,$P$,$B$)
        forall $r \in B\ :\ p \cap r \neq \emptyset$:
            $B = B \backslash \{r\}$
            BREAK($r$,$p$,$Q$)
            $B = B \cup Q$
    $C = B$

\end{lstlisting}
\caption{Algoritmo DSOP}
\end{figure}

How can I make the commands like "while","if" and "forall" in bold and the functions that are written in capital letters in a way that distinguishes them from the rest of the code?

Answer 1

As mentioned in the comment, there are better alternatives for typesetting pseudo-code or algorithms. If you still want to stick to the listings package, you could use the following options for formatting:

\lstset{
    alsoletter={-},
    keywords=[1]{while,if,forall},
    keywords=[2]{BUILD-SOP,WEIGHT,SORP,BREAK, OPT},
    keywordstyle=[1]{\bfseries},
    keywordstyle=[2]{\slshape},
    columns=flexible
}

alsoletter={-} makes listings treat the hyphen character as if it were a letter, so you can use it in keywords/identifiers more easily. Then the keywords option defines a set of special keywords (each set denoted by a number in square brackets), for which different styles can be assigned via the keywordstyle option. More fancy styles are possible; listings e.g. allows to give a separate style for all words/identifiers beside the defined keywords.

Finally, I suggest to use columns=flexible for listings with proportional fonts, as this makes identifiers have their natural width and so prevents bad innerword spacing.

The above setting applied to your example results in: