title: How to declare arrays in python3
body: <p>I want to declare an array in python3. I tried but I got an error</p>
  
  <pre><code>Python 3.6.7 (default, Oct 22 2018, 11:32:17)
  [GCC 8.2.0] on linux
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; ip_pb=[]
  &gt;&gt;&gt; ip_pb[0]="0111111100000000000000011110001"
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  IndexError: list assignment index out of range
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>After,I did this,it is working</p>
  
  <pre><code>&gt;&gt;&gt; ip_pb=[""]
  &gt;&gt;&gt; ip_pb[0]="0111111100000000000000011110001"
  &gt;&gt;&gt; print(ip_pb)
  ['0111111100000000000000011110001']
  </code></pre>
  
  <p>But,I am looking for an another method. If we don't know how many values in the array, we can't declare the array in above method.</p>