title: why getenv() can get name resolved without a std::?
body: <p>getenv() has a C++ implementation which can be included in the header file . So it is a member of namespace std. However, the getenv() function can be get resolved correctly in my code even without a std::getenv(), which means my follow program can be compiled and run without any error and warning. So why getenv() as a name member of namespace std can get resolved without std::? My OS and compiler is Ubuntu 12.04 i386 and g++ 4.8.1 respectively.</p>
  
  <pre><code>#include &lt;cstdlib&gt;
  #include &lt;iostream&gt;
  
  int main()
  {
      char * path_env;
  
      path_env = getenv("PATH"); //without a name resolve operation std::getenv()
  
      std::cout &lt;&lt; path_env &lt;&lt; std::endl;
  
      return 0;
  }
  </code></pre>