is_null

Exemple

Vérifiez si la variable est nul:

 <span class="token php language-php"><span class="token delimiter important"><? Php</span>
<span class="token variable">$ a</span> <span class="token operator">=</span> <span class="token number">0</span> <span class="token punctuation">;</span>
<span class="token keyword">Echo</span> <span class="token string double-quoted-string">"a is"</span> <span class="token operator">.</span> <span class="token function">is_null</span> <span class="token punctuation">(</span> <span class="token variable">$ a</span> <span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span>

<span class="token variable">$ b</span> <span class="token operator">=</span> <span class="token constant">null</span> <span class="token punctuation">;</span>
<span class="token keyword">Echo</span> <span class="token string double-quoted-string">"B est"</span> <span class="token operator">.</span> <span class="token function">is_null</span> <span class="token punctuation">(</span> <span class="token variable">$ b</span> <span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span>

<span class="token variable">$ c</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"null"</span> <span class="token punctuation">;</span>
<span class="token keyword">Echo</span> <span class="token string double-quoted-string">"C est"</span> <span class="token operator">.</span> <span class="token function">is_null</span> <span class="token punctuation">(</span> <span class="token variable">$ c</span> <span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span>

<span class="token variable">$ d</span> <span class="token operator">=</span> <span class="token constant">null</span> <span class="token punctuation">;</span>
<span class="token keyword">Echo</span> <span class="token string double-quoted-string">"d est"</span> <span class="token operator">.</span> <span class="token function">is_null</span> <span class="token punctuation">(</span> <span class="token variable">$ d</span> <span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

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Exemple d'explication:

La valeur de la variable $ a est 0, pas nul, donc is_null ($ a) renvoie false. Les valeurs des variables $ b et $ d sont nuls, donc les deux is_null ($ b) et is_null ($ d) renvoient vrai. La valeur de la variable $ c est une chaîne "null", pas null, donc is_null ($ c) renvoie false.