thinkphp present Label

present label used to determine whether a variable has been defined usage:

Marble platform accuracy class

1. <present name="name">
2. name已经赋值
3. </present>

If the judgment is not assigned, you can use:

1. <notpresent name="name">
2. name还没有赋值
3. </notpresent>

The above can be merged into two tabs:

1. <present name="name">
2. name已经赋值
3. <else />
4. name还没有赋值
5. </present>

tag name attribute present system variables can be used directly, for example:

1. <present name="Think.get.name">
2. $_GET['name']已经赋值
3. </present>