why should i put `android:layout_width="0px"` when i use a`ndroid:layout_weight` property? For example following is my main.xml file , and in that i used `android:layout_width="wrap_content"`, and everything works fine, so why `android:layout_width="0px"` should be used when i am using the layout\_weight property?

```
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:orientation="horizontal">
<EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/editText" android:hint="enter your name"
        android:layout_weight="3"/>
<Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send"
        android:id="@+id/button"
        android:layout_weight="0"/>
</LinearLayout>

```

and this is how my layout looks:
![enter image description here](https://i.stack.imgur.com/2M30o.png)