Some of fine string methods I wish were in C++

main.cpp

#include <string>
#include <vector>


class String {
  public:
  static bool startsWith(std::string string, std::string subString) {
    if (string.substr(0, subString.size()) == subString) return true;
    else return false;
  }

  static std::vector<std::string> split(std::string string, std::string match) {
    std::vector<std::string> result;
    int matchSize = match.size();
    int lastIndex = 0;
    for (int index = 0; index < string.size(); index++) {
      if (index == string.size() - match.size() + 1) {
        result.push_back(string.substr(lastIndex, string.size() - lastIndex));
        break;
      }
      if (string.substr(index, matchSize) == match) {
        result.push_back(string.substr(lastIndex, index - lastIndex));
        lastIndex = matchSize + index;
      }
    }
    return result;
  }

  static std::string replace(std::string string, std::string match, std::string replace) {
    std::string result;
    int matchSize = match.size();
    int lastIndex = 0;
    int matchCounter = 0;
    for (int index = 0; index < string.size(); index++) {
      if (matchCounter != 0) {
        if (matchCounter == match.size() - 1) matchCounter = 0;
        else matchCounter++;
      }
      else if (index == string.size() - match.size()) {
        result.append(replace);
        break;
      }
      else if (string.substr(index, matchSize) == match && matchCounter == 0) {
        result.append(replace);
        lastIndex = matchSize + index;
        matchCounter++;
      }
      else {
        result.push_back(string[index]);
      }
    }
    return result;
  }

  static std::string strip(std::string string) {
    std::string result;
    for (char character: string) {
      if (character != ' ' && character != '\n') {
        result.push_back(character);
      }
    }
    return result;
  }

  static bool contains(std::string string, char keyword) {
    bool result = false;
    for (char character: string) {
      if (character == keyword) {
        result = true;
      }
    }
    return result;
  }

  static std::string extract(std::string string, char start, char end) {
    std::string result;
    bool resultStart = false;
    for (char character: string) {
      if (resultStart && character == end) {
        break;
      }
      else if (resultStart) {
        result.push_back(character);
      }
      else if (character == start) {
        resultStart = true;
      }
    }
    return result;
  }
};