php取出数组单个值

php取出数组单个值
1.数组arr
var_dump(arr) 值如下:

array (size=3)
  "delete" => 
    array (size=3)
      0 => string "HBSFlyRecode20170222-101501.txt" (length=31)
      1 => string "HBSFlyRecode20170222-105502.txt" (length=31)
      2 => string "HBSFlyRecode20170222-108803.txt" (length=31)
  "new" => 
    array (size=3)
      0 => string "HBSFlyRecode20170223-101504.txt" (length=31)
      1 => string "HBSFlyRecode20170223-105505.txt" (length=31)
      2 => string "HBSFlyRecode20170223-108806.txt" (length=31)
  "old" => 
    array (size=3)
      0 => string "HBSFlyRecode20170221-101507.txt" (length=31)
      1 => string "HBSFlyRecode20170221-105508.txt" (length=31)
      2 => string "HBSFlyRecode20170221-108809.txt" (length=31)

echo $arr["old"][0];
打印出: HBSFlyRecode20170221-101507.txt

但是如果arr是对象形式 , 打印结果如下:
var_dump(arr)

object(stdClass)[1]
  public "delete" => 
    array (size=3)
      0 => string "HBSFlyRecode20170222-101501.txt" (length=31)
      1 => string "HBSFlyRecode20170222-105502.txt" (length=31)
      2 => string "HBSFlyRecode20170222-108803.txt" (length=31)
  public "new" => 
    array (size=3)
      0 => string "HBSFlyRecode20170223-101504.txt" (length=31)
      1 => string "HBSFlyRecode20170223-105505.txt" (length=31)
      2 => string "HBSFlyRecode20170223-108806.txt" (length=31)
  public "old" => 
    array (size=3)
      0 => string "HBSFlyRecode20170221-101507.txt" (length=31)
      1 => string "HBSFlyRecode20170221-105508.txt" (length=31)
      2 => string "HBSFlyRecode20170221-108809.txt" (length=31)

就不能使用 $arr[‘old’][0] 取值了 , 可以使用arr对象和数组通用的foreach方式取值:

function getValue($arr){

    foreach($arr as $key => $value){
        if(is_array($value)){
            getValue($value);
        }else{
            echo $value."<br>";
        }

    }
}

如果arr为对象形式 , 可以考录将对象转为数组形式 , 这里提供一种快捷方式:

1. $object_json = json_encode($arr);得到的是对象
   $json = json_encode($arr,true);得到的是纯json
2. json_decode($object_json) 和 json_decode($json)得到的是数组对象
    json_decode($object_json,true) 和 json_decode($json,true)得到的是数组

综上 , 可以将数组对象转为数组的方式:

arr=jsondecode(jsonencode($arr = json_decode(json_encode($arr,true),true);

项目中发现此问题 , 建议大家在php中将json和array转换时 , json_encode() 和 json_decode()的第二个参数要加 true , 即:

json_encode(arr,true);jsondecode($arr,true); json_decode($json,true);
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