Mfrhtyj

How to set a font size in listing when I have these settings in the preamble?

documentclass[12pt,a4paper]{report}

usepackage[most]{tcolorbox}

newtcbinputlisting[auto counter,list inside=lol,list type={lstlisting}]{mylisting}[3]{%

  listing file={#3},

  title=Listing,

  colback=white,

  colframe=gray!75!black,

  fonttitle=bfseries,

  listing only,

  breakable,

  title={Soubor thetcbcounter: #2},

  #1

}

newcommand{listingsfont}{basicstyle=ttfamilytiny} 



begin{document}

mylisting[label=s]{s}{s.txt}

 end{document}

File s.txt:

x = 5;<br>

y = 6;<br>

z = x + y;

I tried

newtcbinputlisting[auto counter,list inside=lol,list type={lstlisting}]{mylisting}[3]{%

  listing file={#3},

  title=Listing,

  colback=white,

  colframe=gray!75!black,

  fonttitle=bfseries,

  fontsize=footnotesize,

  listing only,

  breakable,

  title={Soubor thetcbcounter: #2},

  #1

}

There is an error and

newcommand{listingsfont}{basicstyle=ttfamilytiny} 

that does not do anything - the font size remains the same.

As already explained by Christian Hupfer in his answer to Setting space and font in tcbinputlisting, the font style (including size and font family) for the code display can be set with basicstyle in listings. In an tcolorbox environment options to listings can be passed on with listing option, so that we end up with

listing options={basicstyle=tinyttfamily},

In total

documentclass[12pt,a4paper]{report}

%usepackage{filecontents}

begin{filecontents*}{jobname.txt}

x = 5;

y = 6;

z = x + y;

end{filecontents*}



usepackage[most]{tcolorbox}

newtcbinputlisting[auto counter,list inside=lol,list type={lstlisting}]{mylisting}[3]{%

  listing file={#3},

  title=Listing,

  colback=white,

  colframe=gray!75!black,

  fonttitle=bfseries,

  listing only,

  breakable,

  title={Soubor thetcbcounter: #2},

  listing options={basicstyle=tinyttfamily},

  #1

}



begin{document}

mylisting{Lorem}{jobname.txt}

end{document}

I must say that I find tiny a wee bit hard to read, scriptsize or footnotsize is probably the smallest I would go (with the usual settings). You may also want to adjust the margins a bit so that the code does not get overwhelmed by the vast space around it.