Avec l'extension `xstring` : \documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmO{1}O{red}}{% \IfSubStr[#3]{#1}{#2}{% \IfSubStr[#3]{#1}{#2}{% test if string occures n times in the string \StrBefore[#3]{#1}{#2}% \textcolor{#4}{#2}% \StrBehind[#3]{#1}{#2}% }{% #1 }% } \begin{document} \cmdFormat{coucoucou}{cou}[2][red] \cmdFormat{coucoucou}{cou}[3][green] \cmdFormat{coucoucou}{cou}[4][cyan] \cmdFormat{coucoucou}{cou} \cmdFormat{fvghjwerjfh}{cou} \end{document} ![alt text][1] [1]: https://texnique.fr/osqa/upfiles/Screenshot_2021-11-20_at_13.31.56.png

Avec l'extension `xstring` : \documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmO{1}O{red}}{% \IfSubStr{#1}{#2}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2}% \IfSubStr[#3]{#1}{#2}{% \StrBefore[#3]{#1}{#2}% \textcolor{#4}{#2}% \StrBehind[#3]{#1}{#2}% }{% #1 }% } \begin{document} \cmdFormat{coucoucou}{cou}[2][red] \cmdFormat{coucoucou}{cou}[3][green] \cmdFormat{coucoucou}{cou}[4][cyan] \cmdFormat{coucoucou}{cou} \cmdFormat{fvghjwerjfh}{cou} \end{document} ![alt text][1] [1]: https://texnique.fr/osqa/upfiles/Screenshot_2021-11-20_at_13.31.56.png

Avec l'extension `xstring` : \documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmO{1}O{red}}{% \IfSubStr{#1}{#2}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2}% }{% #1 }% } \begin{document} \cmdFormat{coucoucou}{cou}[2][red] \cmdFormat{coucoucou}{cou}[3][green] \cmdFormat{coucoucou}{cou} \cmdFormat{fvghjwerjfh}{cou} \end{document} ![alt text][1] [1]: https://texnique.fr/osqa/upfiles/Screenshot_2021-11-20_at_13.31.56.png

\documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmO{1}O{red}}{% \IfSubStr{#1}{#2}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2}% }{% #1 }% } \begin{document} \cmdFormat{coucoucou}{cou}[2][red] \cmdFormat{coucoucou}{cou}[3][green] \cmdFormat{coucoucou}{cou} \cmdFormat{fvghjwerjfh}{cou} \end{document}\end{document} ![alt text][1] [1]: https://texnique.fr/osqa/upfiles/Screenshot_2021-11-20_at_13.31.56.png

\documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmO{1}O{red}}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2} \IfSubStr{#1}{#2}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2}% }{% #1 }% } \begin{document} \cmdFormat{coucoucou}{cou}[2][red] \cmdFormat{coucoucou}{cou}[3][green] \cmdFormat{coucoucou}{cou} \end{document} \cmdFormat{fvghjwerjfh}{cou} ![alt text][1] [1]: https://texnique.fr/osqa/upfiles/Screenshot_2021-11-20_at_13.28.17.png \end{document}

\documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmO{1}O{red}}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2} } \begin{document} \cmdFormat{coucoucou}{cou}[2][red] \cmdFormat{coucoucou}{cou}[3][green] \cmdFormat{coucoucou}{cou} \end{document}\end{document} ![alt text][1] [1]: https://texnique.fr/osqa/upfiles/Screenshot_2021-11-20_at_13.28.17.png

\documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmmm}{% \NewDocumentCommand{\cmdFormat}{mmO{1}O{red}}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2} } \begin{document} \cmdFormat{coucoucou}{cou}{2}{red} \cmdFormat{coucoucou}{cou}[2][red] \cmdFormat{coucoucou}{cou}[3][green] \cmdFormat{coucoucou}{cou} \end{document}

\documentclass{article} \usepackage{xcolor} \usepackage{xstring} \NewDocumentCommand{\cmdFormat}{mmmm}{% \StrBefore[#3]{#1}{#2}\textcolor{#4}{#2}\StrBehind[#3]{#1}{#2} } \begin{document} \cmdFormat{coucoucou}{cou}{2}{red} \end{document}