c++ syntax compiling error -

i new programmer whos run compilling error dont understand , hoping somone can me understand why error

31 f:\c++ programming\chapter 13\exercises\exercise 32.cpp no match 'operator||' in '(((std::operator== [with _chart = char, _traits = std::char_traits<char>, _alloc = std::allocator<char>](((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >*)(&letter))), ((const char*)"a")) || std::operator== [with _chart = char, _traits = std::char_traits<char>, _alloc = std::allocator<char>](((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >*)(&letter))), ((const char*)"e"))) || std::operator== [with _chart = char, _traits = std::char_traits<char>, _alloc = std::allocator<char>](((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >*)(&letter))), ((const char*)"i"))) || std::operator== [with _chart = char, _traits = std::char_traits<char>, _alloc = std::allocator<char>](((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)((const std::basic_string<char, std::char_traits<char>, std::allocator<char> >*)(&letter))), ((const char*)"o"))) || letter'  

code

#include <iostream> #include <string> using namespace std;   main() { string word = ""; string letter = " "; int count = 7; string temp = ""; int x = 0; //end declair  cout << "please enter word: "; getline(cin, word); count = word.length(); letter = word.substr(0, 1);  if(letter == "a" || letter == "e" || letter == "i" || letter == "o" || letter == "u") {     word.insert(count, "-way");     cout <<"word starting vowel "<<word<<endl; }     while(letter != "a" && letter != "e" && letter != "i" && letter != "o" &&     letter != "u"||         letter == "y") {     x = 0;     while(x < count)     {          letter = word.substr(0, 1);         word.insert(count, "-");         if(letter == "a" || letter == "e" || letter == "i" || letter == "o" ||//error here   letter || "u"|| letter == "y") //error iss here         {             temp = letter;             cout <<letter <<" ------------------------"<<endl;             word.erase(x, 1);             cout <<word <<" ------------------------"<<endl;             word.insert(x, letter);             cout <<word <<" ------------------------"<<endl;              letter = word.substr(0, 1);          }         x += 1;       }         cout <<"word starting letter "<<word<<endl;                } system("pause"); } 

|| letter || "u")// 

// try

|| letter == "u")//