title: cmake string begins with a caret(^) and ends with a dollar sign($)?
body: <p>I saw a strange cmake line that contains a tring begins with "^" and ends with "$". However, it is not a regular expression, but rather a if statement. It's like this:</p>
  
  <pre><code>  if ("^${CMAKE_SOURCE_DIR}$" STREQUAL "^${PROJECT_SOURCE_DIR}$")
  </code></pre>
  
  <p>Can you tell what does this means? Is it necessary to add the caret and dollar sign to compare the two strings?</p>
  
  <p>Thanks at first.</p>