Boost: How to use + in C POSIX regex interface


Boost: How to use + in C POSIX regex interface



I am trying to use BOOST.Regex POSIX Compatible C API's. I am using regcomp() to match an expression like a+, which should match aa and aaa, while using cflags=REG_BASIC. I have regcomp( reg, "a+", REG_BASIC) but it is not working.


regcomp()


a+


aa


aaa


cflags=REG_BASIC


regcomp( reg, "a+", REG_BASIC)



I found a link stating that + is not part of the POSIX standard. But I found in Boost POSIX Basic regular expression documentation an Emacs variation that supports + syntax.


+


+



How can I use + in POSIX Basic Regular Expressions? Or in other words, enable Emacs variation.


+



References:





You do not need the + quantifier since you may use {1,}. + is an extension for some POSIX regex implementations (as in GNU sed), and is not portable.
– Wiktor Stribiżew
Jul 2 at 13:37


+


{1,}


+





Well, if you plan to use emacs "flavor", use boost::regex::emacs and enjoy +.
– Wiktor Stribiżew
Jul 2 at 13:50


emacs


boost::regex::emacs


+





@WiktorStribiżew Actually I am using the POSIX Compatible C API's as the APIs are called from c code. Is there a way to use boost::regex::emacs from c code?
– Mohamed Elsayed
Jul 2 at 15:22


boost::regex::emacs





It seems you need REG_EXTENDED rather than REG_BASIC then.
– Wiktor Stribiżew
Jul 2 at 16:35


REG_EXTENDED


REG_BASIC









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