Position actuelle: Accueil> Derniers articles> Rencontrer une incompatibilité de type? Découvrez quels types de problèmes doivent être prêts à l'attention lors de l'utilisation de MySQLI_RESULT :: $ Longueurs

Rencontrer une incompatibilité de type? Découvrez quels types de problèmes doivent être prêts à l'attention lors de l'utilisation de MySQLI_RESULT :: $ Longueurs

gitbox 2025-08-28 
<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// Cette partie du code n&#39;a rien à voir avec le contenu du texte，Par exemple, des fins uniquement</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Commencez à exécuter le script...\n"</span></span><span>;
</span><span><span class="hljs-meta">?&gt;</span></span><span>

&lt;hr&gt;

</span><span><span class="hljs-meta">&lt;?php</span></span><span>
<span class="hljs-comment">/*
Un décalage de type rencontré？jeter un coup d&#39;œil mysqli_result::$lengths À quels types de problèmes doivent être prêts à l&#39;attention lors de l&#39;utilisation
*/</span>

<span class="hljs-comment">/**
 * mysqli_result::$lengths est un tableau，Contient la longueur des données correspondant à chaque champ dans l&#39;ensemble de résultats。
 * Faites attention lorsque vous utilisez，Types et scénarios d&#39;utilisation de ces valeurs de longueur。
 */</span>

</span><span><span class="hljs-variable">$mysqli</span></span><span> = </span><span><span class="hljs-keyword">new</span></span><span> </span><span><span class="hljs-title function_ invoke__">mysqli</span></span><span>(</span><span><span class="hljs-string">"localhost"</span></span><span>, </span><span><span class="hljs-string">"user"</span></span><span>, </span><span><span class="hljs-string">"password"</span></span><span>, </span><span><span class="hljs-string">"testdb"</span></span><span>);

</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;connect_error) {
    </span><span><span class="hljs-keyword">die</span></span><span>(</span><span><span class="hljs-string">"Échec de la connexion: "</span></span><span> . </span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;connect_error);
}

</span><span><span class="hljs-variable">$sql</span></span><span> = </span><span><span class="hljs-string">"SELECT id, name, description FROM products"</span></span><span>;
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">query</span></span><span>(</span><span><span class="hljs-variable">$sql</span></span><span>);

</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$result</span></span><span> </span><span><span class="hljs-keyword">instanceof</span></span><span> mysqli_result) {
    </span><span><span class="hljs-comment">// $lengths est un tableau d&#39;entiers，L&#39;élément correspond à la longueur d&#39;octet de chaque champ</span></span><span>
    </span><span><span class="hljs-variable">$lengths</span></span><span> = </span><span><span class="hljs-variable">$result</span></span><span>-&gt;lengths;

    </span><span><span class="hljs-comment">// Exemple：Obtenez le tableau de longueur et imprimez</span></span><span>
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Type de tableau de longueur de champ: "</span></span><span> . </span><span><span class="hljs-title function_ invoke__">gettype</span></span><span>(</span><span><span class="hljs-variable">$lengths</span></span><span>) . </span><span><span class="hljs-string">"\n"</span></span><span>;
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Contenu de la longueur du champ：\n"</span></span><span>;
    </span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$lengths</span></span><span>);

    <span class="hljs-comment">/*
     * Points clés pour les questions de type：
     * 1. $lengths est un tableau，Et chaque élément est un entier（int）。
     * 2. Ces longueurs sont des octets，Remarque la fonction de longueur de chaîne strlen Le nombre de caractères qui peuvent être obtenus est différent，En particulier les personnages multilingue。
     * 3. $lengths Les tableaux sont uniquement utilisés mysqli::store_result Ou il est valable lors de la tampon du résultat par défaut，utiliser mysqli_use_result Non disponible quand。
     * 4. Assurez-vous de confirmer avant de visiter $result C&#39;est efficace mysqli_result Objet，sinon $lengths Aucune existence ou erreur。
     */</span>

    </span><span><span class="hljs-comment">// 进一步Exemple：utiliser长度信息处理数据</span></span><span>
    </span><span><span class="hljs-keyword">while</span></span><span> (</span><span><span class="hljs-variable">$row</span></span><span> = </span><span><span class="hljs-variable">$result</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">fetch_assoc</span></span><span>()) {
        </span><span><span class="hljs-keyword">foreach</span></span><span> (</span><span><span class="hljs-variable">$row</span></span><span> </span><span><span class="hljs-keyword">as</span></span><span> </span><span><span class="hljs-variable">$field</span></span><span> =&gt; </span><span><span class="hljs-variable">$value</span></span><span>) {
            </span><span><span class="hljs-variable">$idx</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_search</span></span><span>(</span><span><span class="hljs-variable">$field</span></span><span>, </span><span><span class="hljs-title function_ invoke__">array_keys</span></span><span>(</span><span><span class="hljs-variable">$row</span></span><span>));
            </span><span><span class="hljs-variable">$len</span></span><span> = </span><span><span class="hljs-variable">$lengths</span></span><span>[</span><span><span class="hljs-variable">$idx</span></span><span>] ?? </span><span><span class="hljs-literal">null</span></span><span>;

            </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Champs '<span class="hljs-subst">{$field}</span></span></span><span>' La longueur de valeur de（octet）pour：</span><span><span class="hljs-subst">{$len}</span></span><span>\n";
            </span><span><span class="hljs-comment">// Faites attention au $len 是octet长度，Pas nécessairement égal au nombre de caractères de chaîne</span></span><span>
            </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Nombre de caractères de chaîne："</span></span><span> . </span><span><span class="hljs-title function_ invoke__">mb_strlen</span></span><span>(</span><span><span class="hljs-variable">$value</span></span><span>, </span><span><span class="hljs-string">'UTF-8'</span></span><span>) . </span><span><span class="hljs-string">"\n"</span></span><span>;
        }
    }

    </span><span><span class="hljs-variable">$result</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">free</span></span><span>();
} </span><span><span class="hljs-keyword">else</span></span><span> {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"La requête a échoué ou pas de résultats。\n"</span></span><span>;
}

</span><span><span class="hljs-variable">$mysqli</span></span><span>-&gt;</span><span><span class="hljs-title function_ invoke__">close</span></span><span>();
</span><span><span class="hljs-meta">?&gt;</span></span><span>

&lt;hr&gt;

</span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// Cette partie du code n&#39;a rien à voir avec le contenu du texte，Par exemple, des fins uniquement</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Fin de l&#39;exécution du script。\n"</span></span><span>;
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>
Connexe
Derniers articles