Errors with eval ()-php Tutorial

Php eval () error ()

 '400','name'=>'kuke','time'=>'1024')";$res="1+3";var_dump($res);$v=eval($res);var_dump($v);echo $v;foreach($v as $key=>$val){echo $key."=".$val;}//-------------------------------------------echo "
";//--------------------------------------------$res=array('price'=>'400','name'=>'kuke','time'=>'1024');var_dump($res);echo "
";foreach($res as $key=>$val){echo $key."=".$val."
";}

This is the result
String (3) "1 + 3"
Parse error: syntax error, unexpected $ end in D: \ myweb \ array. php (5): eval () 'd code on line 1
Bool (false)
Warning: Invalid argument supplied for foreach () in D: \ myweb \ array. php on line 8

Array (3) {["price"] => string (3) "400" ["name"] => string (4) "kuke" ["time"] => string (4) "1024 "}
Price = 400
Name = kuke
Time = 1024
Can someone help me analyze why something went wrong?

Reply to discussion (solution)

$v = eval("return $res;");

Eval () returns NULL. unless a value is returned in the executed code, the function returns the value passed to return. If there is a parsing error in the executed code, eval () returns FALSE, and the subsequent code will be executed normally. You cannot use set_error_handler () to capture parsing errors in eval.

Definition and usage

The eval () function calculates the string according to the PHP code.

The string must be a valid PHP code and must end with a semicolon.

If the return statement is not called in the code string, NULL is returned. If a parsing error exists in the code, the eval () function returns false.
Therefore, write $ v = eval ("return $ res ;");

Warning: Invalid argument supplied for foreach () in D: \ myweb \ array. php on line 8
This error occurs because foreach can only traverse arrays and objects. If you input $ v as the bool value, an error is returned.

1.
$ Res = "1 + 3 ";
Eval ("\ $ v = \" $ res \";");
Var_dump ($ v );

2.
$ V no data