# About regexp

**URL:** <https://www.ruby-forum.com/t/about-regexp/152937>\
**Category:** Ruby\
**Created:** [November 10, 2008, 5:17am UTC](https://www.ruby-forum.com/t/about-regexp/152937 "2008-11-10T05:17:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Kyung\_won\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/47e85d/32.png) [@Kyung\_won\_C](https://www.ruby-forum.com/u/Kyung_won_C)\
**Post date:** [November 10, 2008, 5:17am UTC](https://www.ruby-forum.com/t/about-regexp/152937/1 "2008-11-10T05:17:46Z")

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> > “aaabbxccc”.sub(/bb(.)c/, “\1.upcase”)  
> > =\> “aaax.upcasecc” # I expect ‘aaaXcc’

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# Help Me^^

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**Author:** ![Kyung\_won\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/47e85d/32.png) [@Kyung\_won\_C](https://www.ruby-forum.com/u/Kyung_won_C)\
**Post date:** [November 10, 2008, 5:44am UTC](https://www.ruby-forum.com/t/about-regexp/152937/2 "2008-11-10T05:44:09Z")

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From: Kyung won Cheon [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)]

# \>\> “aaabbxccc”.sub(/bb(.)c/, “\1.upcase”)

# =\> “aaax.upcasecc” # I expect ‘aaaXcc’

consider,

> “\1.upcase”  
> =\> “\1.upcase”

> “\1”.upcase  
> =\> “\1”

try,

“aaabbxccc”.sub(/bb(.)c/) {$1.upcase}

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<div class="post-metadata">

**Author:** ![Kyung\_won\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/47e85d/32.png) [@Kyung\_won\_C](https://www.ruby-forum.com/u/Kyung_won_C)\
**Post date:** [November 10, 2008, 5:45am UTC](https://www.ruby-forum.com/t/about-regexp/152937/3 "2008-11-10T05:45:19Z")

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Kyung won Cheon wrote:

> > > “aaabbxccc”.sub(/bb(.)c/, “\1.upcase”)  
> > > =\> “aaax.upcasecc” # I expect ‘aaaXcc’

> > > “aaabbxccc”.sub(/bb(.)c/) {$1.upcase}  
> > > =\> “aaaXcc”