Tutorial :Get String Between 2 Strings


How can I get a string that is between two other declared strings, for example:

String 1 = "[STRING1]"  String 2 = "[STRING2]"  


"832h0ufhu0sdf4[STRING1]I need this text here[STRING2]afyh0fhdfosdfndsf"  

How can I get the "I need this text here"?


Since this is homework, only clues:

  • Find index1 of occurrence of String1
  • Find index2 of occurrence of String2
  • Substring from index1+lengthOf(String1) (inclusive) to index2 (exclusive) is what you need
    • Copy this to a result buffer if necessary (don't forget to null-terminate)


Might be a good case for std::regex, which is part of C++11.

#include <iostream>  #include <string>  #include <regex>    int main()  {      using namespace std::string_literals;        auto start = "\\[STRING1\\]"s;      auto end = "\\[STRING2\\]"s;        std::regex base_regex(start + "(.*)" + end);        auto example = "832h0ufhu0sdf4[STRING1]I need this text here[STRING2]afyh0fhdfosdfndsf"s;        std::smatch base_match;      std::string matched;        if (std::regex_search(example, base_match, base_regex)) {          // The first sub_match is the whole string; the next          // sub_match is the first parenthesized expression.          if (base_match.size() == 2) {              matched = base_match[1].str();          }      }      std::cout << "example: \""<<example << "\"\n";      std::cout << "matched: \""<<matched << "\"\n";    }  


example: "832h0ufhu0sdf4[STRING1]I need this text here[STRING2]afyh0fhdfosdfndsf"  matched: "I need this text here"  

What I did was create a program that creates two strings, start and end that serve as my start and end matches. I then use a regular expression string that will look for those, and match against anything in-between (including nothing). Then I use regex_match to find the matching part of the expression, and set matched as the matched string.

For more info, see http://en.cppreference.com/w/cpp/regex and http://en.cppreference.com/w/cpp/regex/regex_search


Use strstr http://www.cplusplus.com/reference/clibrary/cstring/strstr/ , with that function you will get 2 pointers, now you should compare them (if pointer1 < pointer2) if so, read all chars between them.

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