请教一个数组取值问题

比如现在有一个数组$qs_array，里面有3个对象。
我想取第一个对象中的值是$qs_array[0]->id吗?
不知道为什么$qs_array[0]是null.

解决方案 »

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前面建议你贴出来，你最好运行下var_dump($qs_array)或者print_r($qs_array)，把结果贴上，比较好……数据多至少贴几个样本
$qs_array = array(object1,object2,object3);
array(3) { [1]=> object(stdClass)#372 (46) { ["category"]=> string(1) "0" ["sortorder"]=> string(1) "0" ["password"]=> string(0) "" ["fullname"]=> string(7) "ECNU-CE" ["shortname"]=> string(4) "ECNU" ["idnumber"]=> string(0) "" ["summary"]=> string(4) "ECNU" ["format"]=> string(4) "site" ["showgrades"]=> string(1) "1" ["modinfo"]=> string(6) "a:0:{}" ["newsitems"]=> string(1) "3" ["teacher"]=> string(6) "教师" ["teachers"]=> string(6) "教师" ["student"]=> string(6) "学生" ["students"]=> string(6) "学生" ["guest"]=> string(1) "0" ["startdate"]=> string(1) "0" ["enrolperiod"]=> string(1) "0" ["numsections"]=> string(1) "0" ["er"]=> string(1) "0" ["maxbytes"]=> string(1) "0" ["showreports"]=> string(1) "0" ["visible"]=> string(1) "1" ["hiddensections"]=> string(1) "0" ["groupmode"]=> string(1) "0" ["groupmodeforce"]=> string(1) "0" ["defaultgroupingid"]=> string(1) "0" ["lang"]=> string(0) "" ["theme"]=> string(0) "" ["cost"]=> string(0) "" ["currency"]=> string(3) "USD" ["timecreated"]=> string(1) "0" ["timemodified"]=> string(10) "1278035605" ["metacourse"]=> string(1) "0" ["requested"]=> string(1) "0" ["restrictmodules"]=> string(1) "0" ["expirynotify"]=> string(1) "0" ["expirythreshold"]=> string(1) "0" ["notifystudents"]=> string(1) "0" ["enrollable"]=> string(1) "1" ["enrolstartdate"]=> string(1) "0" ["enrolenddate"]=> string(1) "0" ["enrol"]=> string(0) "" ["defaultrole"]=> string(1) "0" ["coursetime"]=> string(1) "0" ["id"]=> int(1) } [2]=> object(stdClass)#371 (46) { ["category"]=> string(1) "2" ["sortorder"]=> string(3) "100" ["password"]=> string(0) "" ["fullname"]=> string(13) "大学英语1" ["shortname"]=> string(7) "大英1" ["idnumber"]=> string(0) "" ["summary"]=> string(0) "" ["format"]=> string(5) "weeks" ["showgrades"]=> string(1) "1" ["modinfo"]=> string(1553) "a:6:{i:1;O:8:"stdClass":10:{s:2:"id";s:1:"1";s:2:"cm";i:1;s:3:"mod";s:5:"forum";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:45:"%E6%96%B0%E9%97%BB%E8%AE%A8%E8%AE%BA%E5%8C%BA";}i:10;O:8:"stdClass":10:{s:2:"id";s:1:"3";s:2:"cm";i:10;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:5:"Test1";}i:12;O:8:"stdClass":10:{s:2:"id";s:1:"5";s:2:"cm";i:12;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:9:"333333333";}i:13;O:8:"stdClass":10:{s:2:"id";s:1:"6";s:2:"cm";i:13;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:3:"333";}i:16;O:8:"stdClass":10:{s:2:"id";s:1:"9";s:2:"cm";i:16;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:3:"ree";}i:2;O:8:"stdClass":10:{s:2:"id";s:1:"1";s:2:"cm";i:2;s:3:"mod";s:10:"assignment";s:7:"section";s:1:"1";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:36:"%E5%90%AC%E5%8A%9B%E7%BB%83%E4%B9%A0";}}" ["newsitems"]=> string(1) "5" ["teacher"]=> string(6) "教师" ["teachers"]=> string(6) "教师" ["student"]=> string(6) "学生" ["students"]=> string(6) "学生" ["guest"]=> string(1) "0" ["startdate"]=> string(10) "1278115200" ["enrolperiod"]=> string(1) "0" ["numsections"]=> string(2) "10" ["er"]=> string(1) "0" ["maxbytes"]=> string(7) "2097152" ["showreports"]=> string(1) "0" ["visible"]=> string(1) "1" ["hiddensections"]=> string(1) "0" ["groupmode"]=> string(1) "0" ["groupmodeforce"]=> string(1) "0" ["defaultgroupingid"]=> string(1) "0" ["lang"]=> string(0) "" ["theme"]=> string(0) "" ["cost"]=> string(0) "" ["currency"]=> string(3) "USD" ["timecreated"]=> string(10) "1278035991" ["timemodified"]=> string(10) "1278041551" ["metacourse"]=> string(1) "0" ["requested"]=> string(1) "0" ["restrictmodules"]=> string(1) "0" ["expirynotify"]=> string(1) "0" ["expirythreshold"]=> string(6) "864000" ["notifystudents"]=> string(1) "0" ["enrollable"]=> string(1) "1" ["enrolstartdate"]=> string(1) "0" ["enrolenddate"]=> string(1) "0" ["enrol"]=> string(0) "" ["defaultrole"]=> string(1) "0" ["coursetime"]=> string(2) "40" ["id"]=> int(2) } [3]=> object(stdClass)#370 (46) { ["category"]=> string(1) "2" ["sortorder"]=> string(2) "99" ["password"]=> string(0) "" ["fullname"]=> string(13) "大学英语2" ["shortname"]=> string(7) "大英2" ["idnumber"]=> string(0) "" ["summary"]=> string(0) "" ["format"]=> string(5) "weeks" ["showgrades"]=> string(1) "1" ["modinfo"]=> string(2747) "a:11:{i:3;O:8:"stdClass":10:{s:2:"id";s:1:"2";s:2:"cm";i:3;s:3:"mod";s:5:"forum";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:45:"%E6%96%B0%E9%97%BB%E8%AE%A8%E8%AE%BA%E5%8C%BA";}i:4;O:8:"stdClass":10:{s:2:"id";s:1:"1";s:2:"cm";i:4;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:5:"TEST1";}i:5;O:8:"stdClass":10:{s:2:"id";s:1:"2";s:2:"cm";i:5;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:6:"TESTT2";}i:6;O:8:"stdClass":10:{s:2:"id";s:1:"2";s:2:"cm";i:6;s:3:"mod";s:10:"assignment";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:2:"aa";}i:7;O:8:"stdClass":10:{s:2:"id";s:1:"3";s:2:"cm";i:7;s:3:"mod";s:10:"assignment";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:2:"bb";}i:8;O:8:"stdClass":10:{s:2:"id";s:1:"4";s:2:"cm";i:8;s:3:"mod";s:10:"assignment";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:2:"cc";}i:9;O:8:"stdClass":10:{s:2:"id";s:1:"5";s:2:"cm";i:9;s:3:"mod";s:10:"assignment";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:2:"dd";}i:11;O:8:"stdClass":10:{s:2:"id";s:1:"4";s:2:"cm";i:11;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:5:"Test3";}i:14;O:8:"stdClass":10:{s:2:"id";s:1:"7";s:2:"cm";i:14;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:3:"121";}i:15;O:8:"stdClass":10:{s:2:"id";s:1:"8";s:2:"cm";i:15;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:4:"w2ww";}i:17;O:8:"stdClass":10:{s:2:"id";s:2:"10";s:2:"cm";i:17;s:3:"mod";s:4:"quiz";s:7:"section";s:1:"0";s:7:"visible";s:1:"1";s:9:"groupmode";s:1:"0";s:10:"groupingid";s:1:"0";s:16:"groupmembersonly";s:1:"0";s:5:"extra";s:0:"";s:4:"name";s:7:"rtttttt";}}" ["newsitems"]=> string(1) "5" ["teacher"]=> string(6) "教师" ["teachers"]=> string(6) "教师" ["student"]=> string(6) "学生" ["students"]=> string(6) "学生" ["guest"]=> string(1) "0" ["startdate"]=> string(10) "1278547200" ["enrolperiod"]=> string(1) "0" ["numsections"]=> string(2) "10" ["er"]=> string(1) "0" ["maxbytes"]=> string(7) "2097152" ["showreports"]=> string(1) "0" ["visible"]=> string(1) "1" ["hiddensections"]=> string(1) "0" ["groupmode"]=> string(1) "0" ["groupmodeforce"]=> string(1) "0" ["defaultgroupingid"]=> string(1) "0" ["lang"]=> string(0) "" ["theme"]=> string(0) "" ["cost"]=> string(0) "" ["currency"]=> string(3) "USD" ["timecreated"]=> string(10) "1278466052" ["timemodified"]=> string(10) "1278466052" ["metacourse"]=> string(1) "0" ["requested"]=> string(1) "0" ["restrictmodules"]=> string(1) "0" ["expirynotify"]=> string(1) "0" ["expirythreshold"]=> string(6) "864000" ["notifystudents"]=> string(1) "0" ["enrollable"]=> string(1) "1" ["enrolstartdate"]=> string(1) "0" ["enrolenddate"]=> string(1) "0" ["enrol"]=> string(0) "" ["defaultrole"]=> string(1)
我用foreach是能全部读出来的，不过我现在只想取其中某一个
你的对象数组，下标你注意下，是从1开始的所以取值$qs_array[1]->category;其他类似
问题在于现在$qs_array明明是有值的，用$qs_array[1]就是null了
echo $qs_array[1]->fullname;//这样的结果是null?
echo $qs_array[3]->id;//注意：array(3)
array(3) { [1]=> object(数组下标是从1开始的。
应该是你组织数组时设定KEY的时候的问题吧。
要么就设定一个和对象相关的KEY，$arr['objectname']=$object，要么就$arr[]=$object;让其自增。