title: Regex to describe binary numbers
body: <p>I want to have a regular expression to describe all binary numbers (consisting only of 0 and 1). </p>
  
  <p>So it should work for 100 0 101001 11 000
  but not for the 1 and 0 parts in hello1001and011. It really should only match to all digit numbers.</p>
  
  <p>I wanted to write ^(0|1)(0|1)*(0|1)$ to mark that it should begin and end with a zero or one and in the middle can be arbitrary many 0 and 1 but it doesn't match anything.</p>
  
  <p>In my lecture we just saw operations like | , + , * , ^ , $ , . , as well as \d and \w. </p>
  
  <p>Can someone please help me to find my error/give me a working regular expression?</p>