Find duplicate entry in string in c++

Question

I have different type of string and I need to find out the duplicate entry in this string. Different type of string

string aStr= "1.1,1.2,1.3, 1"; //output should be duplicate entry
string aStr= "1.1,1.2,1.3"; //Ouput NO duplicate entry
string aStr= "1,2,1"; //o/p duplicate entry
string aStr = "1,2,3";//output No duplicate 

I have tried as 
std::vector < std::string > aOutString;
std::set <int> full_list;
std::set <std::string> aEntryInDouble;
int aNum1;
boost::split(aOutString, aStr , boost::is_any_of(","));
for(size_t it = 0; it < aOutString.size(); ++it)
{
if (aOutString[it].find('.') != std::string::npos)
{
 //If entry is like "1.1,1.2,1.3"
  if( !aEntryInDouble.insert(aOutString[it]).second )
  {
     aDup = false;
     break;
  }
}
 else
{
//For entry "1,2,1"
 aNum1 = std::atoi(aOutString[it].c_str());
 if(aNum1)
 {
 if( !full_list.insert(aNum1).second )
 {
 aDup = false;
 break;
 }
 }

1. I am not able to find out the solution for entry string "string aStr= "1.1,1.2,1.3, 1"; Please help me to find out the solution.

Thanks,

Answer 1

Here's an algorithm:

Split the input on commas. You will create a list of everything that is comma-delimited. You will then create a set from the list that may contain duplicates. This will remove all duplicates for you. If the list's length is equal to the set's length, there are no duplicates. Otherwise, constructing the set removed duplicates and it is shorter than the list.

---

Here's the code in C++. I took the tokenize from this answer and made a few modifications. Also, here's the coliru.

#include <iostream>
#include <vector>
#include <string>
#include <unordered_set>

std::vector<std::string> split(const std::string& str, const std::string& delimiters = ",") {
    std::vector<std::string> tokens;

    // Skip delimiters at beginning.
    auto lastPos = str.find_first_not_of(delimiters, 0);
    // Find first "non-delimiter".
    auto pos = str.find_first_of(delimiters, lastPos);

    while(std::string::npos != pos || std::string::npos != lastPos) {
        // Found a token, add it to the vector.
        tokens.push_back(str.substr(lastPos, pos - lastPos));
        // Skip delimiters.  Note the "not_of"
        lastPos = str.find_first_not_of(delimiters, pos);
        // Find next "non-delimiter"
        pos = str.find_first_of(delimiters, lastPos);
    }

    return tokens;
}

bool has_dupes(const std::vector<std::string>& v) {
    std::unordered_set<std::string> s(v.cbegin(), v.cend());
    return s.size() != v.size();
}

std::string detect_duplicates(const std::string& s) {
    auto v = split(s);
    return has_dupes(v) ? "duplicates" : "no duplicates";
}

int main() {
    // dupes
    std::string dupes = "1,2,3,4,1";
    std::cout << detect_duplicates(dupes) << '\n';

    // no dupes
    std::string no_dupes = "1,2,3";
    std::cout << detect_duplicates(no_dupes) << '\n';           
}