strpos() is closing while true

Question

I loop a query. I check if the value of each record contains within any string (in the case $message). The problem is that when the value is found, in this case within the ELSE, while is closed for some reason. I need verification to continue to be done on all records, until the end of records.

$query = "select id, id_usuario texto from palavra";
$result = mysql_query($query);
while($palavras = mysql_fetch_array($result)) {
   $valor = $palavras["texto"];
   $iduser = $palavras["id_usuario"];

   if(!strpos(strtolower($mensagem), strtolower($valor))) {
      echo " não.<BR>";
   } else {
      echo " sim.<BR>";

     $query = "select nome from usuario where id = $iduser";
     $result = mysql_query($query);
     $user_dados = mysql_fetch_row($result);

   }

}

If I take the internal consultation, the loop remains normal as expected. But I need the query.

Answer 1

The problem seems to happen in the second consultation due to the reuse of the variable $result in the second consultation change her name.

To avoid false positives with the function strpos() use the operator === so it compares the value and type. Without it if the string is found at zero position your code will be diverted to the Else block incorrectly.

$query = "select id, id_usuario texto from palavra";
$result = mysql_query($query); //<--- primeira ocorrência

//aqui na segunda 'volta' do while $result já pode ser false ou não devolver as chaves texto e id_usuario
while($palavras = mysql_fetch_array($result)) { 
   $valor = $palavras["texto"];

   if(strpos(strtolower($mensagem), strtolower($valor)) === false) {
      echo " não.<BR>";
   } else {

      $query = "select nome from usuario where id = $iduser";
      $result = mysql_query($query); //reatribução indevida.
      $user_dados = mysql_fetch_row($result);
   }

}

Answer 2

Must be a Exception and the errors are off so you didn’t notice, turn on the PHP errors, when in development, in production use ini_set('display_errors', '0');, is probably some mistake in using mysql_fetch_array or in your query or something next to this.

Another problem that may have occurred was with the variable $mensagem, check if it exists and is in it "scope" from the script you quoted.

Do so in development, put at the top of your file:

<?php
ini_set('display_errors', 1);
error_reporting(E_ALL|E_STRICT);

Something else strpos only returns false if nothing is found, if you do this for example:

strpos('abc', 'a');

It will return zero and as ! considers both 0, how much false how much NULL how much '' (empty string) so it should be used like this:

   if (strpos(strtolower($mensagem), strtolower($valor)) === false) {
        echo " não.<BR>";
   } else {
        echo " sim.<BR>";

        $query = "select nome from usuario where id = $iduser";
        $result = mysql_query($query);
        $user_dados = mysql_fetch_row($result);
   }

I noticed you used strtolower, but that’s expendable if you use it like this stripos:

   if (stripos($mensagem, $valor) === false) {
        echo " não.<BR>";
   } else {
        echo " sim.<BR>";

        $query = "select nome from usuario where id = $iduser";
        $result = mysql_query($query);
        $user_dados = mysql_fetch_row($result);
   }

Another important thing is to no longer use the old PHP API for mysql, prefer PDO or mysqli, read:

• Difference between mysql_connect() and mysqli_connect() functions in php

Answer 3

Your problem is because our friend PHP interprets the "0" in the same way as the "false". So when he finds the substring at the beginning of the string he returns 0 (which php also understands as false).

change your code to:

while($palavras = mysql_fetch_array($result)) {
   $valor = $palavras["texto"];

   if(strpos(strtolower($mensagem), strtolower($valor)) === false) {
      echo " não.<BR>";
   } else {
      echo " sim.<BR>";
   }

}

That’s right with 3 "===".