Code Review for Hangman in C++
I'm by far no expert, and I might be wrong on some of my statements, so take them as a basis for discussion. Anyway, I am trying to learn about code quality in C++ myself, so I'm giving it a shot.


printVector should take the argument as const-ref, because the vector is not supposed to be changed in the function call.
Consider using an iterator to loop through the vector in printVector. However, in a small-scale program like this I don't see this as a big issue. In larger programs, it might help you to make a function more general. And thanks to C++11's auto, it will be very readable -- even more so if you use a range-based for loop.
You're using the vector&lt;int&gt; guessed to store the chars from userGuess. Why not a vector&lt;char&gt; to store char? Would also make the type cast to (char) in printVector unnecessary.
Also you're mixing C-arrays and STL's std::vector, C-strings (char *) and std::string. Try to stick to the STL versions throughout. If you are using a C++11 capable compiler, you can even initialize the std::vector the same way as you're doing with the C-array now.
You are using curly braces {} in for loops and if/else statements only when absolutely required. Most style guides encourage using braces for every for/if/else block, or at most allow omitting them for one-line "blocks". The reason is readability (you can always expect to find a } where a longer block ends) and editability (It's easy to forget adding the braces when adding a line to the supposed for/if/else block).
It doesn't look like idiomatic C++ to compare a bool variable with == as in if(letterCorrect == false). You should use something like if (! letterCorrect) instead.
You should add a return 0; statement when the user is hanged. As far as I know it isn't required for the main function, but as you're already returning with return 0; when the user guesses the word, you should also do so at the end of the function.
The condition if (compWord == compHiddenWord) is wrong. You're looping over the array elements, but then you're comparing the pointer to the 0th element of the array to the std::string, instead of comparing the array elements. If you follow my suggestion above and change compHiddenWord to std::string, then you can omit the loop and simply write if(compWord == compHiddenWord) (Edit: As I learned, it also works correctly for comparisons of char* and std::string, so I deleted my example for by-character comparison)
You're using a as a loop index. While this isn't wrong, C++ programmers would typically use i or j for this purpose. 
Edit: Your hangman array goes from 0 to 9 -- but in the while loop you never reach the 9 thanks to the hangManPos != 9 condition. Therefore, you will never print the completely hanged hangman.


Let me know what you think!