is_string

实例

检查变量是否为字符串类型：

<span class="token php language-php"><span class="token delimiter important"><?php</span>  
<span class="token variable">$a</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"Hello"</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"a is "</span> <span class="token operator">.</span> <span class="token punctuation">(</span><span class="token function">is_string</span><span class="token punctuation">(</span><span class="token variable">$a</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token string single-quoted-string">'a string'</span> <span class="token punctuation">:</span> <span class="token string single-quoted-string">'not a string'</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">$b</span> <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"b is "</span> <span class="token operator">.</span> <span class="token punctuation">(</span><span class="token function">is_string</span><span class="token punctuation">(</span><span class="token variable">$b</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token string single-quoted-string">'a string'</span> <span class="token punctuation">:</span> <span class="token string single-quoted-string">'not a string'</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">$c</span> <span class="token operator">=</span> <span class="token number">32</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"c is "</span> <span class="token operator">.</span> <span class="token punctuation">(</span><span class="token function">is_string</span><span class="token punctuation">(</span><span class="token variable">$c</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token string single-quoted-string">'a string'</span> <span class="token punctuation">:</span> <span class="token string single-quoted-string">'not a string'</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">$d</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"32"</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"d is "</span> <span class="token operator">.</span> <span class="token punctuation">(</span><span class="token function">is_string</span><span class="token punctuation">(</span><span class="token variable">$d</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token string single-quoted-string">'a string'</span> <span class="token punctuation">:</span> <span class="token string single-quoted-string">'not a string'</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">$e</span> <span class="token operator">=</span> <span class="token constant boolean">true</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"e is "</span> <span class="token operator">.</span> <span class="token punctuation">(</span><span class="token function">is_string</span><span class="token punctuation">(</span><span class="token variable">$e</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token string single-quoted-string">'a string'</span> <span class="token punctuation">:</span> <span class="token string single-quoted-string">'not a string'</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">$f</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"null"</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"f is "</span> <span class="token operator">.</span> <span class="token punctuation">(</span><span class="token function">is_string</span><span class="token punctuation">(</span><span class="token variable">$f</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token string single-quoted-string">'a string'</span> <span class="token punctuation">:</span> <span class="token string single-quoted-string">'not a string'</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">$g</span> <span class="token operator">=</span> <span class="token string double-quoted-string">""</span><span class="token punctuation">;</span>  
<span class="token keyword">echo</span> <span class="token string double-quoted-string">"g is "</span> <span class="token operator">.</span> <span class="token punctuation">(</span><span class="token function">is_string</span><span class="token punctuation">(</span><span class="token variable">$g</span><span class="token punctuation">)</span> <span class="token operator">?</span> <span class="token string single-quoted-string">'a string'</span> <span class="token punctuation">:</span> <span class="token string single-quoted-string">'not a string'</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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