Find words between brackets in a sentence with some constraints (inner brackets) regex

Question

I have a the following sentence:

[[Image:Levellers declaration and standard.gif|thumb|200px|Woodcut from a [[Diggers]] document by william everard]]

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Regular expression

I am using the following regular expression in order to extract the words that are between brackets [[ ]]:

regex = "\\[\\[(.*?)\\]\\]"

The output should be equal to the following sentence:

Image:Levellers declaration and standard.gif|thumb|200px|Woodcut from a [[Diggers]] document by william everard

I want to only take into consideration the left-most brackets ]]

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Problem

regex will extract [[Image:Levellers declaration and standard.gif|thumb|200px|Woodcut from a [[Diggers]] and will leave document by william everard]].

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Question

How can I ignore the inner brackets represented by ]].

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Update V0

I wrote a simple program inspired by BalancedParentheses.cpp in order to locate the beginning and ending of the text between brackets in a string.

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Source code

    #include <stack>
    #include <iostream>
    #include <vector>
    #include <string>
    
    using namespace std;
    bool AreParanthesesBalanced(string exp)
    { 
        stack<char>  S;
        vector<pair<int, int>> index;
        int end;
        vector<int> start;
        for(int i = 0; i < exp.length(); i++)
        {
           if(exp[i] == '(' || exp[i] == '{' || exp[i] == '[')
           {
             S.push(exp[i]);
             start.push_back(i);
            }
                    
            else if(exp[i] == ')' || exp[i] == '}' || exp[i] == ']')
            {
                if(S.empty() || !ArePair(S.top(),exp[i]))
                {
                  return false;
                }
                  
               else
               {
                 S.pop();
                 end = i;
                 index.push_back(make_pair(start[start.size() - 1] ,end));
                 start.pop_back();
               }      
            }
         }
                
         for(int i = 0; i < index.size(); i ++)
         {
            cout << index[i].first <<"  "<< index[i].second << endl;
         }
       return S.empty() ? true:false;
   }
        
        int main()
        {
          string exp = "[[Image:Levellers declaration and standard.gif|thumb|200px|Woodcut from a [[Diggers]] document by william everard]] ";
        
           bool x = reParanthesesBalanced(exp);
           return 0;
        }

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Output

75  83
74  84
1  113
0  114

Answer 1

I think your issue is that you use a lazy (*?) quantifier, instead of a greedy (*) one.

The lazy quantifier will stop as soon as it meets the first ]] in the string, even if it is not the final one.

You can simply modify your regex to this :

regex = "\\[\\[(.*)\\]\\]"