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Regex Overview Examples

Usage in different languages

As the actual use of regular expressions is quite language specific there are separate cheat sheets:

Standards

Regex Variants

VariantUsed ByMeta CharactersBack References
POSIX BREgrep, sed^ $ \{\} \[\] \(\) . * GNU extension: \+ \?\1 ... \9
POSIX EREegrep, awk, gawk^ $ {} [] () . * + ? |gawk: \\1 .. \\9
Perl REPerl, C, PHP, Python, Ruby... Every programming language using PCRE^ $ {} () . * + ? |Based on language
Perl\g1 \g2 ... \g-1 \g-2 ... \g{-1} \g{-2} ... \g{name} \k{name} \g'name' \k'name'
PHP\\1 .. \\9 $1 .. $99 ${1} .. ${99}
Python\1 .. \99 \g1 .. \g99 \g (?P...) (?P=name)

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