title: R : str_replace_all function not converting "2010-12-31+10" to "2011-01-10"
body: <p>I have a string like this:</p>
  
  <pre><code>str1 &lt;- "get all securities in portfolio port1 on date 2010-12-31 where field value of Close on 2010-12-31+10 less than 2000"
  </code></pre>
  
  <p>I am trying to convert "2010-12-31+10" to "2011-01-10" in <code>str1</code>.
  I tried <code>str_replace_all</code> method of <code>stringr</code> package
  But i didnt get the output. </p>
  
  <pre><code>&gt; str_replace_all(str1,"2010-12-31+10","2011-01-10")
  [1] "get all securities in portfolio port1 on date 2010-12-31 where field value of Close on 2010-12-31+10 less than 2000"
  </code></pre>
  
  <p>What is the reason for that?</p>