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How Can I Efficiently Match Multiple Words in a String Using C \'s `std::regex`?

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Release: 2024-11-29 12:51:11
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How Can I Efficiently Match Multiple Words in a String Using C  's `std::regex`?

Matching Multiple Results with std::regex

Matching multiple occurrences of words in a string can be challenging with regular expressions. Although the expression "(bS*b){0,}" appears to match all consecutive words in a string, it may not yield the desired output. Instead, an iterative approach is recommended.

Following is the revised code:

#include <iostream>
#include <string>
#include <regex>

int main() {
    regex exp("(\b\S*\b)");
    smatch res;
    string str = "first second third forth";

    string::const_iterator searchStart(str.cbegin());
    while (regex_search(searchStart, str.cend(), res, exp)) {
        cout << (searchStart == str.cbegin() ? "" : " ") << res[0];
        searchStart = res.suffix().first;
    }
    cout << endl;

    return 0;
}
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In this updated code, we use a while loop to iterate through the string while performing regular expression searches. The loop starts by setting the searchStart iterator to the string's beginning. Then, within each iteration:

  1. The regex_search function searches for the first occurrence of the pattern within the substring starting at searchStart.
  2. If a match is found, we print the matching word.
  3. We update the searchStart iterator to start searching after the matched word.

By iterating through the string until no more matches are found, we can output all the words one by one.

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