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

Matching Multiple Results with std::regex

This article discusses a scenario where a user attempts to match every word in a given string using the C standard library regex engine (std::regex). The user employs the regex pattern "(bS*b)" to achieve this, but encounters unexpected behavior.

The Problem

The initial regex pattern provided, "(bS*b)", encapsulates words bounded by word boundaries (b) and non-whitespace characters (S). However, when combined with the regex_search function, this pattern fails to account for multiple potential matches within the input string.

The Solution

To address this issue, it is necessary to iterate over the input string while continuously applying regex_search. This ensures that all matches can be detected and captured. The modified code below demonstrates this approach:

{
    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 <p>In this revised code, an iterator, searchStart, is initialized to the beginning of the input string. The regex_search function is called iteratively, with searchStart serving as the search starting position. If a match is found, the match is printed, and searchStart is adjusted to the position following the matched text. This process continues until no more matches can be found.</p>

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