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# Switch 中的多个default默认值

在PHP7之前的版本中，Switch可以有多个default默认值。代码如下：

```php
<?php
$a = 10;
$b = 0;

switch(true)
{
    default:
        $b += 1;
        break;
    default:
        $b += 2;
}

echo 'b is' . $b;
```

但是从PHP7开始，这样写会产生 Fatal 级别错误，错误内容如下：

```
Fatal error: Switch statements may only contain one default clause in ...
```