Vector unique not working on char*

[Ducky]

Trying to sort out and remove duplicates from a char* vector.

Sorting working but the duplicates are still there.

#include <iostream>     // cout

#include <algorithm>    // unique, distance
#include <string>
#include <iterator>     // std::back_inserter
#include <set>
#include <vector>       // vector
using namespace std;
 

bool strcmpFunc(const char *c1, const char *c2)
{
    return strcmp(c1, c2) < 0;
}
 
char *url[]=
{
    "bbbb",
    "bbbb",
    "aaa",
    "ccccccc",
    "a",
    "aaa"
};
 
int main ()
{
    vector <char*> v;
    vector<char*>::iterator it;

    int size =  sizeof(url)/sizeof(url[0]);

    for (int i=0; i< size; ++i)
        v.push_back(url[i]);

    cout << v.size()  <<'\n';

    sort(v.begin(), v.end(), strcmpFunc);
    v.erase(std::unique(v.begin(), v.end()), v.end());

    cout << "vector after sorting:\n\n";
    for (it=v.begin(); it!=v.end(); ++it)
        cout << *it << '\n';
    cout << '\n';    

return 0;
}

[laserlight]

I will start with the same advice as in your other recent thread: use std::string.

That said, the problem is that you are using the version of std::unique that compares elements using operator==, hence you are comparing pointers, not strings. You should write another predicate that compares null terminated C-style strings with strcmp, then pass that to std::unique.

But using std::string would be better.

[Ducky]

Yes, it's true!

Again I fell upon a code with windows API in it that took wchar_t* as parameter and I didn't think of rewriting it with std::wstring.

But now I will do it. Thanks Laserlight!

[Elysia]

C++ has many ways to interface with C. For strings, you can simply use .c_str(). Don't fall back on using C constructs simply because working with some C stuff. That will hurt you in the end.