phpinclude publicifcookiephp;接收信息$tool = $_GETgame;echo $free;写入$dkwj = fopenjsontoolgametxtw;fwrite$dkwj$tool;fclose$dkwj;echo scriptalert修改成功！;windowhistoryback-1;script;Notice Undefined variable fr

It seems that the variable $free is not defined in your code. You are trying to echo it on line 5, but it has not been assigned a value before that. Make sure to define and assign a value to the $free variable before trying to use it.