PHP array reference passing question

As shown in the highlighted part of the picture, how can the operation here directly change the value of the $initialcount array element? Is it feasible to add the & symbol?

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As shown in the highlighted part of the picture, how can the operation here directly change the value of the $initialcount array element? Is it feasible to add the & symbol?

Your code can be modified. . There are no parameters passed, it is global in the current code.

This operation can originally assign a value to $initialcount. What went wrong? &According to my understanding, it can only be used in the parameters of the declared function.