title: RegExp help (for PHP)
body: <p>I am working on a little "development" language for my personal use. I do not plan to make it advanced at all (although I don't know what will happen at later points), but I've run into a problem.</p>
  
  <p>I am not very experienced with RegExp and I want to use it to check whatever a part of the code is defining a new variable or running function. In this case, I need a RegExp that will check if the user is defining a variable.</p>
  
  <p>So, lets say I have a part like this: <strong>$abcd = 5</strong></p>
  
  <p>Now, the RegExp should meet the next criteria:
    - It should check if the first letter is "$" (that's easy: "\$")
    - Now, the letters after "$" (lets call them variable name) are the problem. Variable
      name can contain letters [a-z, A-Z], numbers [0-9] and underscores [_]
    - The next thing, space between the variable name and "=" can be infinitely long (it can
      be one space ( ), or a millions of spaces - that should make no difference
    - Than comes the equal sign (this is easy as well - "\=")
    - The same as in the third one applies for space after equal sign
    - And at the end variable value. There should be no RegExp validation for this.</p>
  
  <p>Thanks in advance!</p>