从PHP运行python脚本给我null输出

i want to open and execute a python file using php . for this reason i’m using xamp . my php and python both files resides in htdocs folder. here is the code.

$output = shell_exec("python untitled6.py");
var_dump($output);

i have also tried different methods like

$python = 'C:\\Users\\Imama\\Anaconda2\\python.exe' ;
$pyscript= 'E:\\xamp\\htdocs\\untitled6.py' ;
$cmd = "$python $pyscript";
echo $cmd;
$result= exec($cmd);

i want help regarding plx :(