title: error: use of undeclared identifier VS Code
body: <p>I am simply trying to compile a simple program including a .cpp and .h(.hpp for VS code Purposes)
  Whenever I Put the implementation for the Constructor in the .hpp file and not include the .cpp, the code will compile. However, whenever i separate the Implementation into the .cpp file i get</p>
  <pre><code>error: use of undeclared identifier 'std' LinkedChar::(std::string s)
  </code></pre>
  <p>I have tried including headguards but use #pragma once, i still get the same error.
  Here is my main.cpp</p>
  <pre><code>#include &quot;LinkList.hpp&quot;
  
  
  int main()
  {
  
  
    LinkedChar(&quot;h&quot;);
  
  
    return 0;
  }
  </code></pre>
  <p>Here is my .hpp File</p>
  <pre><code>#pragma once
  #include &quot;LinkList.cpp&quot;
  #include &lt;iostream&gt;
  #include &lt;string&gt;
  
  //Create a LinkList
  class Node
  {
    public:
  
  
    Node *next;
    char data; //The data will hold a character 
  };
  
  class LinkedChar
  {   
    public:
    //LinkedChar(): head(NULL), tail(NULL){}
    LinkedChar(std::string s);
  
  
    private:
    Node* tail;
    Node* head;
  };
  </code></pre>
  <p>my cpp file</p>
  <pre><code>#include &quot;LinkList.hpp&quot;
  
  LinkedChar::LinkedChar(std::string s)
  {
  
    int length = s.length();
    Node* temp = new Node;
    head = nullptr;
  
  
  
    if(length==1)//If there is only one letter
    {
       temp-&gt;data=s[0];
       head = temp;     
       tail = temp;
       temp-&gt;next = nullptr;
       std::cout&lt;&lt;temp-&gt;data;
  
    }
  
    else
    {
       for(int i = 1; i&lt;length; i++)
  
       temp-&gt;data = s[i];
       temp-&gt;next = nullptr;
       tail = temp;
  
    }
  
  }
  </code></pre>