# Punctuation in biblatex between volume and number

I am using biblatex to make bibliography and the number and volume are displayed as volume.number however I want it to be volume:number. I have tried \DeclareFieldFormat[article]{number}{:#1}, but it yields volume.:number and colon appears even if volume is not present.

MWE:

\begin{filecontents}{bibl.bib}

@article{A,
author = {John Doe},
title = {Interesting article},
volume = {10},
number = {100},
pages = {1--20},
journal = {Daily articles},
year = {2020}
}

@article{B,
author = {Jane Doe},
title = {Another Interesting article},
number = {50},
pages = {1--24},
journal = {Monthly articles},
year = {2020}
}

\end{filecontents}

\documentclass[12pt]{article}

\usepackage{filecontents}

\usepackage[russian]{babel}

\usepackage[
backend = biber,
language = russian,
]{biblatex}

\renewbibmacro{in:}{%
\ifentrytype{article}{}{\printtext{\bibstring{in}\intitlepunct}}}

\begin{document}

\nocite{*}

Some text

\printbibliography

\end{document}


This is easily done with styles from my biblatex-ext bundle. They define the punctuation command \volnumdelim for exactly this job.

With biblatex-ext you can even replace your redefinition of the in: bibmacro by the option articlein=false.

Each standard style has a biblatex-ext equivalent, to which you can switch with no change in output. In the MWE you are using (implicitly) style=numeric,, so the biblatex-ext style you want is style=ext-numeric,.

\documentclass[12pt]{article}
\usepackage[russian]{babel}

\usepackage[backend = biber, style=ext-numeric,
articlein=false]{biblatex}

\begin{filecontents}{\jobname.bib}
@article{A,
author  = {John Doe},
title   = {Interesting article},
volume  = {10},
number  = {100},
pages   = {1--20},
journal = {Daily articles},
year    = {2020},
}
@article{B,
author  = {Jane Doe},
title   = {Another Interesting article},
number  = {50},
pages   = {1--24},
journal = {Monthly articles},
year    = {2020},
}
\end{filecontents}

\begin{document}
\nocite{*}
Some text

\printbibliography
\end{document}


If for some reason you don't want to or can not use biblatex-ext, you can try the following redefinition

\newcommand*{\volnumdelim}{\addcolon}