CODEWITHSUNDEEP
c++regexboost
Sturm
Sturm

Reputation: 4125

boost regex capture group and replace

I am trying to expand a CamelCase string this way: CamelCase >> Camel Case, using boost.

string Utils::ExpandCamelCase(string & str)
{
    static boost::regex camelCaseExpandRegex = boost::regex(R"(\B[A-Z]+?(?=[A-Z][^A-Z])|\B[A-Z]+?(?=[^A-Z]))");
    string result = boost::regex_replace(str, camelCaseExpandRegex, "  $1");
    return result;
}

As you see I am trying to capture first group, which should be the upper letter of each word (excluding first one), and to replace it with a space plus that group.

Something is wrong since "ExpandCamelCasePlease" turns into "Expand amel ase lease".

Trying variations I suspect that I am not capturing the group as I should.

What changes do I need to make to expand correctly camel case inserting spaces before capital letters?

Upvotes: 0

Views: 1197

Answers (2)

Michał Turczyn
Michał Turczyn

Reputation: 37377

Use simply (?<=[a-z])(?=[A-Z]).

It uses lookbehind (?<=[a-z]), to see if what is behind is lowercase letter and it looks ahead ((?=[A-Z])) to see if what's ahead it uppercase letter.

Then just replace it with space .

Demo

Upvotes: 1

Nambi_0915
Nambi_0915

Reputation: 1091

Try this,

string Utils::ExpandCamelCase(string & str)
{
static boost::regex camelCaseExpandRegex = boost::regex(R"([A-Z][^ ]+?)(?=[A-Z]|$)");
string result = boost::regex_replace(str, camelCaseExpandRegex, "  $1");
return result;

}

Regex

Upvotes: 2

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