将表单数据放入PHP数组中

Question

I have this form

  <form action = "put the data to a single PHP array" method="post">
    <input name="a" type="text" />
    <input name="b" type="text" />
    <input name="c" type="text" /> 
    <input name="d" type="text" /> 
    <input type="button">
  </form>

the condition is that I want to put the data into a PHP array when the user filled the form and click the submit button. the data should be order the way the text input fields are arranged. how can I do that?

Pls help me with the code. thanks!