CODEWITHSUNDEEP
c++regex
user3724853
user3724853

Reputation: 567

how to modify the regex string

Said a input string

std::string input_string = ";;abc,123;,,;456,def;789,ghi,135,jkl";

I want to get only "number,string" pair within semicolon closure from input string. In this case, "456,def" is the only match.

Here is my code

std::regex regex("(\\d+),([^,;]+)(?:;|$)");
for (std::sregex_iterator it(input_string.begin(), input_string.end(), regex), itEnd; it != itEnd; ++it) {
    std::cout << it->str(1) << ", " << it->str(2) << std::endl;
}

But this code also get "135,jkl" as result

Please help me how to modify the regex string?

Upvotes: 2

Views: 135

Answers (2)

bipll
bipll

Reputation: 11940

So add a non-capturing group for the leading semicolon:

std::regex regex("(?:^|;)(\\d+),([^,;]+)(?=;|$)");

Or, since you're iterating through them anyway, do it in AWK way!

// iterate through ;-separated fields
for(std::sregex_iterator it(
                input_string.begin(), input_string.end(), std::regex("[^;]+"))
            , itEnd
        ; it != itEnd
        ; ++it)
{
    if(std::regex_match(it->str(0), std::regex("\\d+,[^,]*"))) {
        std::cout << it->str(0) << std::endl;
    }
}

Upvotes: 1

CinCout
CinCout

Reputation: 9619

Seems like you are complicating things!

The following simple regex works just fine:

;(\d+,[a-zA-Z]+);

All I am looking for is more than one digit, followed by a comma, followed by more than one alphabet; which is enclosed within semi-colon on either side. Make sure the global flag is turned on to capture all such cases.

P.S.: I assumed that the string part will contain only English alphabets (a to z, case insensitive).

Demo

Upvotes: 0

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