#Know your Standard Library The standard unique algorithm performs exactly this task (and is available in C++03). If we take the argument by value, we can modify it in place, and use the erase-remove idiom:

#include <algorithm>
#include <vector>
template<class T>
std::vector<T> remove_duplicate(std::vector<T> vec) {
 vec.erase(std::unique(vec.begin(), vec.end()), vec.end());
 return vec;
}

Note that the result vector has the same capacity as the input vector. If this is likely to be a problem, then std::unique_copy() could be used to copy values into a new vector, or a move to C++11 would gain the shrink_to_fit() method on your vector.

Know your Standard Library

The standard unique algorithm performs exactly this task (and is available in C++03). If we take the argument by value, we can modify it in place, and use the erase-remove idiom:

#include <algorithm>
#include <vector>
template<class T>
std::vector<T> remove_duplicate(std::vector<T> vec) {
 vec.erase(std::unique(vec.begin(), vec.end()), vec.end());
 return vec;
}

Note that the result vector has the same capacity as the input vector. If this is likely to be a problem, then std::unique_copy() could be used to copy values into a new vector, or a move to C++11 would gain the shrink_to_fit() method on your vector.