我正在尝试对一个对象进行 json_encode，但我希望外部包装器是一个数组而不是一个对象。

我试过了

json_encode($myobject,JSON_OBJECT_AS_ARRAY)

但我的最终结果总是

{
  "SALDOC": [
    {
      "SERIES": null,"TRDR": null,"PAYMENT": "2","SHIPMENT": "","TRNDATE": "2019-03-11 07:57:38","REMARKS": null,"DISC1VAL": "0.0000","SALESMAN": null,"SHIPKIND": null,"CCCCLCOURIERWEIGHT": "1.0000"
    }
  ],"ITELInes": [
    {
      "LINENUM": null,"VAT": null,"MTRUNIT4": null,"MTRCATEGORY": null,"MTRL": null,"QTY1": "1.0000","PRICE": "15.0000"
    }
  ],"MTRDOC": [
    {
      "SHPZIP": "test","SHPCITY": "teset","SHIPPINGADDR": "test","SHPDISTRICT": 100
    }
  ],"SRVLInes": [],"EXPANAL": []
}

如何使外包装成为数组 [] 而不是对象 {}？