Vector push_back on duplicate strings with the help of delimiter - c++

Question

I am trying to read the PATH Environment variable and remove any duplicates that are present in it using vector functionalities such as - sort, erase and unique. But as I've seen vector will delimit each element default by newline. When I get the path as C:\Program Files(x86)\..., its breaking at C:/ Program. This is my code so far:
char *path = getenv("PATH");
char str[10012] = "";
strcpy(str,path);
string strr(str);
vector<string> vec;
stringstream ss(strr);
string s;
while(ss >> s)
{
push_back(s);
}
sort(vec.begin(),vec.end());
vec.erase(unique(vec.begin(),vec.end()),vec.end());
for(unsigned i=0;i<vec.size();i++)
{
cout<<vec[i]<<endl;
}
Is it the delimiter problem? I need to pus_back at every ; and search for duplicates. Can anyone help me in this regard.

Answer 1

I would use a stringstream to chop it up, and the use a set to ensure there are no duplicates.
std::string p { std::getenv("PATH") }
std::set<string> set;
std::stringstream ss { p };
std::string s;
while(std::getline(ss, s, ':')) //this might need to be ';' for windows
{
set.insert(s);
}
for(const auto& elem : set)
std::cout << elem << std::endl;
Should you need to use a vector for some reason, you'd want to sort it with std::sort then remove duplicates with std::unique then erase the slack with erase.
std::sort(begin(vec), end(vec));
auto it=std::unique(begin(vec), end(vec));
vec.erase(it, end(vec));
EDIT: link to docs
http://en.cppreference.com/w/cpp/container/set
http://en.cppreference.com/w/cpp/algorithm/unique
http://en.cppreference.com/w/cpp/algorithm/sort

Answer 2

For this task it is better to use std::set<std::string> which will eliminate duplicates automatically. To read in PATH, use strtok to split it into substrings.

Answer 3

You need to use a different delimiter (':' or ';' to split the directories from the PATH, depending on the system). For instance, you can have a look at the std::getline() function to replace your current while () / push_back loop. This function allows you to specify a custom delimiter and would be a drop-in replacement in your code.

Answer 4

It isn't so much that std::vector<T> is delimiting anything but that the formatted input operator (operator>>()) for strings uses whitespace as delimiters. Other already posted about using std::getline() and the like. There are two other approaches:
Change what is considered to be whitespace for the stream! The std::string input operator uses the stream's std::locale object to obtain a std::ctype<char> facet which can be replaced. The std::ctype<char> facet has functions to do character classification and it can be used to consider, e.g., the character ';' as a space. It is a bit involved but a more solid approach than the next one.
I don't think path components can include newlines, i.e., a simple approach could be to replace all semicolons by newlines before reading the components:
std::string path(std::getenv("PATH"));
std::replace(path.begin(), path.end(), path.begin(), ';', '\n');
std::istringstream pin(path);
std::istream_iterator<std::string> pbegin(pin), pend;
std::vector<std::string> vec(pbegin, pend);
This approach may have the problem that the PATH may contain components which contain spaces: these would be split into individual object. You might want to replace spaces with another character (e.g., the now unused ';') and restore those at an appropriate to become spaces.