title: what is the regular expression for identifying decimal number
body: <p>I have tried writing a code for identifying decimal number in python using regular expression as indicated in the below code.</p>
  
  <p>It is working fine for many case but still failing to identify below inputs </p>
  
  <pre><code>import re
  string = input()
  r = re.compile(r"([+\-.]?\d*\.\d+)\b")
  if(r.match(string)):
      print(True)
  else: 
      print(False)
  </code></pre>
  
  <p>234.2344  ->for this input giving expected results</p>
  
  <p>+.3456468 ->for this input giving expected results</p>
  
  <p>5.34.0  -> for this input it should print False</p>
  
  <p>4+345.0  -> for this input it should print False</p>