Change on PHP7 from PHP5

Question

On PHP7 we know that a variable has to be inizialized with its type, differnet from where we did on php5 that the type was changed according the value set.

If we test this code

  <?php

  /* EAMPLE A */
  $tLisTim="";
  $i=0;
  $tLisTim[$i]=100;
  $i=$i+1;
  $tLisTim[$i]=200;

  var_dump("A");
  var_dump($tLisTim);

  /* EAMPLE B */
  $tLisTim=[];
  $i=0;
  $tLisTim[$i]=100;
  $i=$i+1;
  $tLisTim[$i]=200;

  var_dump("B");
  var_dump($tLisTim);

  ?>

we will get this results:

  PHP 5.6

  string 'A' (length=1)
  array (size=2)
    0 => int 100
    1 => int 200

  string 'B' (length=1)
  array (size=2)
    0 => int 100
    1 => int 200


  PHP 7.1

  string 'A' (length=1)
  string '12' (length=2)

  string 'B' (length=1)
  array (size=2)
    0 => int 100
    1 => int 200

The problem is that in PHP7 there is not warning to help us to migrate correctly all this differences.

How can I detect when we try to use a variable with an incorrect type ?

Thanks,

I would say is_* where * is the type you would expect ? like php.net/manual/en/function.is-array.php. But to be honest why do you have in your code an empty string and expect to change it into array ? — Frankich
– Frankich, Commented Feb 11, 2019 at 17:36
These are probably either notices or warnings, so may not throw an error depending on your error suppressions. Try enabling warning/notice errors in your test environment while migrating to php7. — aynber
– aynber, Commented Feb 11, 2019 at 17:43
Weird, that discrepancy appears to have been introduced in PHP >= 7.1 specifically — MonkeyZeus
– MonkeyZeus, Commented Feb 11, 2019 at 17:47
@aynber I have all errors and notices enabled and I don't get any messages — MonkeyZeus
– MonkeyZeus, Commented Feb 11, 2019 at 17:50
@MonkeyZeus Ah, good to know. It was a guess, since it wasn't something I had run into before. — aynber
– aynber, Commented Feb 11, 2019 at 17:53

MonkeyZeus · Accepted Answer · 2019-02-11 18:10:52Z

There is no warning because PHP 7.1 did not remove support for your code structure:

String modification by character on an empty string now works like for non-empty strings, i.e. writing to an out of range offset pads the string with spaces, where non-integer types are converted to integer, and only the first character of the assigned string is used. Formerly, empty strings where silently treated like an empty array.

http://php.net/manual/en/migration71.incompatible.php#migration71.incompatible.empty-string-modifcation-by-character

This is still perfectly valid:

$tLisTim="";
$tLisTim[0]=100;
$tLisTim[1]=200;

but it behaves differently than before.

Instead of silently converting to an array it sets the first position of the string to 1 and the second position to 2.

This will throw an error:

$tLisTim="";
$tLisTim[]=100;

This will throw a warning:

$tLisTim="";
$tLisTim['g']=100;

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