title: C:\Program was unexpected at this time. Trying to compile C++ library to .dll via .bat file from Visual Studio Command Prompt
body: <p>This question is not connected with specific library but I will try to explain full process what is the issue:</p>
  
  <ol>
  <li>I am trying to compile minkowski.cc code of boost library via bat file like this: <img src="https://i.stack.imgur.com/d5E2n.png" alt="Screenshot1"></li>
  <li>Compiling works fine and I can compile and run 32 bit version.</li>
  <li>The problem happens when I want to compile 64 bit version. Again it is not the issue of library but compiling issue. To compile I open "Visual Studio Community 2017 Command Prompt" (I have C++ development installed), by default compiler is set to x86 - 32 bit version: <img src="https://i.stack.imgur.com/gaQdz.png" alt="Screenshot2"></li>
  <li>To change compiler from 32bit to 64 bit I type: <strong>vcvarsall.bat x86_amd64</strong></li>
  <li>However I get error: <strong>C:\Program was unexpected at this time.</strong>
  <img src="https://i.stack.imgur.com/JTQQa.png" alt="Screenshot3"></li>
  </ol>
  
  <p>I am searching how to change compiler from 32 bit to 64 bit for a week in stack-overflow and google queries but cannot find a correct answer. Please help.</p>