#include <iostream>
    #include <string>
    using namespace std;
 
    class TaintedString : public string {using string::string;};
    class BlessedString : public string {using string::string;};
 
    BlessedString untaintString(TaintedString tstr) {
    //do some sanitation or whatever is necessary
    size_t pos;
    while((pos = tstr.find('\'')) != TaintedString::npos) {
    tstr.erase(pos);
    }
 
    return BlessedString(tstr.c_str());
    }
 
    int main() {
    TaintedString attack = "Mike\'; DROP TABLE users;";
    BlessedString bs = untaintString(attack);
 
    //BlessedString test = attack; //compilation error
 
    std::cout << bs << "\n";
    return 0;
    }

ICAgICNpbmNsdWRlIDxpb3N0cmVhbT4KICAgICNpbmNsdWRlIDxzdHJpbmc+CiAgICB1c2luZyBuYW1lc3BhY2Ugc3RkOwogICAgIAogICAgY2xhc3MgVGFpbnRlZFN0cmluZyA6IHB1YmxpYyBzdHJpbmcge3VzaW5nIHN0cmluZzo6c3RyaW5nO307CiAgICBjbGFzcyBCbGVzc2VkU3RyaW5nIDogcHVibGljIHN0cmluZyB7dXNpbmcgc3RyaW5nOjpzdHJpbmc7fTsKICAgICAKICAgIEJsZXNzZWRTdHJpbmcgdW50YWludFN0cmluZyhUYWludGVkU3RyaW5nIHRzdHIpIHsKICAgIC8vZG8gc29tZSBzYW5pdGF0aW9uIG9yIHdoYXRldmVyIGlzIG5lY2Vzc2FyeQogICAgc2l6ZV90IHBvczsKICAgIHdoaWxlKChwb3MgPSB0c3RyLmZpbmQoJ1wnJykpICE9IFRhaW50ZWRTdHJpbmc6Om5wb3MpIHsKICAgIHRzdHIuZXJhc2UocG9zKTsKICAgIH0KICAgICAKICAgIHJldHVybiBCbGVzc2VkU3RyaW5nKHRzdHIuY19zdHIoKSk7CiAgICB9CiAgICAgCiAgICBpbnQgbWFpbigpIHsKICAgIFRhaW50ZWRTdHJpbmcgYXR0YWNrID0gIk1pa2VcJzsgRFJPUCBUQUJMRSB1c2VyczsiOwogICAgQmxlc3NlZFN0cmluZyBicyA9IHVudGFpbnRTdHJpbmcoYXR0YWNrKTsKICAgIAogICAgLy9CbGVzc2VkU3RyaW5nIHRlc3QgPSBhdHRhY2s7IC8vY29tcGlsYXRpb24gZXJyb3IKICAgIAogICAgc3RkOjpjb3V0IDw8IGJzIDw8ICJcbiI7CiAgICByZXR1cm4gMDsKICAgIH0=