Troubleshooting "Notice: Undefined index", but index appears to be defined

Question

I have this piece of code:

<?php

$pattern = "/<span\b[^>]*>(.*?)</";
$html = file_get_contents("http://www.bicicletapublica.com.ar/mapa.aspx");
$results = array();
preg_match_all($pattern, $html, $results );
$results  = $results[0];
$stations = array();

for($i = 0; $i < count($results)-1;$i++){
    if(!($i & 1)){
        $key = strtolower(str_replace(" ","_",substr($results[$i], 0, -1)));
        $stations["$key"] = str_replace("Cant. Bicicletas disponibles: ","",substr($results[$i+1], 0, -1));

    }
}
print_r($stations);
print_r($stations["retiro"])
?>

And I'm getting this error:

Array ( [retiro] => 40 [aduana] => 26 [derecho] => 27 [plaza_roma] => 8 [plaza_italia] => 29 [parque_lezama] => 31 [obelisco] => 28 [congreso] => 7 [parque_las_heras] => 17 [uca_puerto_madero] => 27 [tribunales] => 25 [plaza_vicente_lopez] => 23 [once] => 27 [pacifico] => 19 [virrey_cevallos] => 26 [plaza_houssay] => 2 [plaza_de_mayo] => 6 [plaza_almagro] => 21 [cmd] => 7 [independencia] => 9 [plaza_san_martin] => 21 )

Notice: Undefined index: retiro in /opt/lampp/htdocs/mejorenbici/index.php on line 17

As you can see, the key retiro was defined, but I don't understand why the undefined index error is triggered.

There has to be more to the story here. Any funny characters in your PHP file? You're not using unicode indices on your array, right? Also, no need to put `$key` in quotes at `$stations["$key"] = str_replace(...`. — Brad, Nov 12 '11 at 21:51
@Brad - When I run that code on my site, I also get the same error on all of the keys in the array. — Jared Farrish, Nov 12 '11 at 21:59
@JaredFarrish, PointedEars figured it out below. For Topicus and you, do not give us errors as rendered by a browser... there was more to it, that was hidden, and viewing source revealed it. — Brad, Nov 13 '11 at 02:47
@Brad - "For Topicus and you" What does this mean? That comment had to do with your initial comment, and as I was further researching the issue (after the comment), PointedEars posted his answer (which I have already upvoted). So I don't know what you mean by "do not give us errors" and you seem to be talking to me to. — Jared Farrish, Nov 13 '11 at 04:05

PointedEars · Accepted Answer · 2011-11-14T17:55:35.677

Look at the HTML source code of the notice (not: error). When running your code in the console with php -a, I am getting:

Array (
  [<span_class="style1">retiro] => <span class="style2">40
  [<span_class="style1">aduana] => <span class="style2">26
  [<span_class="style1">derecho] => <span class="style2">27
  [<span_class="style1">plaza_roma] => <span class="style2">8
  [<span_class="style1">plaza_italia] => <span class="style2">29
  [<span_class="style1">parque_lezama] => <span class="style2">31
  [<span_class="style1">obelisco] => <span class="style2">28
  [<span_class="style1">congreso] => <span class="style2">7
  [<span_class="style1">parque_las_heras] => <span class="style2">17
  [<span_class="style1">uca_puerto_madero] => <span class="style2">27
  [<span_class="style1">tribunales] => <span class="style2">25
  [<span_class="style1">plaza_vicente_lopez] => <span class="style2">23
  [<span_class="style1">once] => <span class="style2">27
  [<span_class="style1">pacifico] => <span class="style2">19
  [<span_class="style1">virrey_cevallos] => <span class="style2">26
  [<span_class="style1">plaza_houssay] => <span class="style2">2
  [<span_class="style1">plaza_de_mayo] => <span class="style2">6
  [<span_class="style1">plaza_almagro] => <span class="style2">21
  [<span_class="style1">cmd] => <span class="style2">7
  [<span_class="style1">independencia] => <span class="style2">9
  [<span_class="style1">plaza_san_martin] => <span class="style2">21
)
PHP Notice: Undefined index: retiro in - on line 19
PHP Stack trace:
PHP   1. {main}() -:0

Do not parse HTML by applying only one Regular Expression only one time; use a markup parser (which can make use of Regular Expressions for greater efficiency).

Do you have permission to reuse that data?

Aha! He didn't give us the plain-text error, but the browser-rendered version. Good call! — Brad, Nov 13 '11 at 02:46
Thanks a lot for the reply! yes, that was the problem. It was parsing in a wrong way the data. — Topicus, Nov 14 '11 at 16:28

score 1 · Answer 2 · answered Nov 12 '11 at 21:56

you should wrap the stations array to make sure you're not entering empty indexes in your array. your error is probably caused by the previous print_r() statement:

print_r($stations);

new logic wrapping:

if (!empty($key)) { $stations["$key"] = str_replace("Cant. Bicicletas disponibles: ","",substr($results[$i+1], 0, -1)); }

this should prevent empty indexes in your array.

Troubleshooting "Notice: Undefined index", but index appears to be defined

2 Answers2