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399 lines
23 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>检查一个断言是否为 FALSE</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.assert" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">assert</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">assert</span> — <span class="dc-title">检查一个断言是否为 <strong><code>FALSE</code></strong></span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.assert-description">
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<h3 class="title">说明</h3>
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<p class="para">PHP 5</p>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>assert</strong></span>
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( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$assertion</code></span>
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[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$description</code></span>
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] ) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">PHP 7</p>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>assert</strong></span>
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( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$assertion</code></span>
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[, <span class="methodparam"><span class="type"><span class="type Throwable">Throwable</span></span> <code class="parameter">$exception</code></span>
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] ) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">
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<span class="function"><strong>assert()</strong></span> 会检查指定的
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<code class="parameter">assertion</code> 并在结果为 <strong><code>FALSE</code></strong> 时采取适当的行动。
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</p>
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<div class="refsect2 unknown-descriptioo" id="refsect2-function.assert-unknown-descriptioo">
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<h4 class="title">Traditional assertions (PHP 5 and 7)</h4>
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<p class="para">
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如果 <code class="parameter">assertion</code> 是字符串，它将会被 <span class="function"><strong>assert()</strong></span> 当做 PHP 代码来执行。
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<code class="parameter">assertion</code> 是字符串的优势是当禁用断言时它的开销会更小，并且在断言失败时消息会包含 <code class="parameter">assertion</code> 表达式。
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这意味着如果你传入了 boolean 的条件作为 <code class="parameter">assertion</code>，这个条件将不会显示为断言函数的参数；在调用你定义的 <span class="function"><a href="assert_options.html" class="function">assert_options()</a></span> 处理函数时，条件会转换为字符串，而布尔值 <strong><code>FALSE</code></strong> 会被转换成空字符串。
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</p>
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<p class="para">
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断言这个功能应该只被用来调试。
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你应该用于完整性检查时测试条件是否始终应该为 <strong><code>TRUE</code></strong>，来指示某些程序错误，或者检查具体功能的存在（类似扩展函数或特定的系统限制和功能）。
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</p>
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<p class="para">
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断言不应该用于普通运行时操作，类似输入参数的检查。
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作为一个经验法则，在断言禁用时你的代码也应该能够正确地运行。
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</p>
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<p class="para">
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<span class="function"><strong>assert()</strong></span> 的行为可以通过 <span class="function"><a href="assert_options.html" class="function">assert_options()</a></span> 来配置，或者手册页面上描述的 .ini 设置。
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</p>
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<p class="para">
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<span class="function"><a href="assert_options.html" class="function">assert_options()</a></span> <strong><code>ASSERT_CALLBACK</code></strong> 配置指令允许设置回调函数来处理失败的断言。
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</p>
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<p class="para">
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<span class="function"><strong>assert()</strong></span> 回调函数在构建自动测试套件的时候尤其有用，因为它们允许你简易地捕获传入断言的代码，并包含断言的位置信息。
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当信息能够被其他方法捕获，使用断言可以让它更快更方便！
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</p>
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<p class="para">
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回调函数应该接受三个参数。
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第一个参数包括了断言失败所在的文件。
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第二个参数包含了断言失败所在的行号，第三个参数包含了失败的表达式（如有任意 — 字面值例如 1 或者 "two" 将不会传递到这个参数）。
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PHP 5.4.8 及更高版本的用户也可以提供第四个可选参数，如果设置了，用于将 <code class="parameter">description</code> 指定到 <span class="function"><strong>assert()</strong></span>。
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</p>
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</div>
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<div class="refsect2 unknown-unknown-descriptiop" id="function.assert.expectations">
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<h4 class="title">Expectations (PHP 7 only)</h4>
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<p class="para">
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<span class="function"><strong>assert()</strong></span> is a language construct in PHP 7, allowing for
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the definition of expectations: assertions that take effect in development
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and testing environments, but are optimised away to have zero cost in
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production.
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</p>
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<p class="para">
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While <span class="function"><a href="assert_options.html" class="function">assert_options()</a></span> can still be used to control
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behaviour as described above for backward compatibility reasons, PHP 7
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only code should use the two new configuration directives to control
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the behaviour of <span class="function"><strong>assert()</strong></span> and not call
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<span class="function"><a href="assert_options.html" class="function">assert_options()</a></span>.
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</p>
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<table class="doctable table">
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<caption><strong>
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PHP 7 configuration directives for <span class="function"><strong>assert()</strong></span>
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</strong></caption>
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<thead>
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<tr>
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<th>Directive</th>
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<th>Default value</th>
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<th>Possible values</th>
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</tr>
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</thead>
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<tbody class="tbody">
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<tr>
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<td>
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<a href="ini.core.html#ini.zend.assertions" class="link">zend.assertions</a>
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</td>
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<td><em>1</em></td>
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<td>
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<ul class="simplelist">
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<li class="member">
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<em>1</em>: generate and execute code (development mode)
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</li>
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<li class="member">
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<em>0</em>: generate code but jump around it at runtime
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</li>
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<li class="member">
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<em>-1</em>: do not generate code (production mode)
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</li>
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</ul>
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</td>
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</tr>
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<tr>
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<td>
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<a href="info.configuration.html#ini.assert.exception" class="link">assert.exception</a>
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</td>
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<td><em>0</em></td>
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<td>
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<ul class="simplelist">
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<li class="member">
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<em>1</em>: throw when the assertion fails, either by
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throwing the object provided as the <code class="parameter">exception</code>
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or by throwing a new <strong class="classname">AssertionError</strong> object if
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<code class="parameter">exception</code> wasn't provided
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</li>
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<li class="member">
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<em>0</em>: use or generate a
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<strong class="classname">Throwable</strong> as described above, but only
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generate a warning based on that object rather than throwing it
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(compatible with PHP 5 behaviour)
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</li>
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</ul>
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</td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.assert-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">assertion</code></dt>
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<dd>
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<p class="para">
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断言。In PHP 5, this must be either a <span class="type"><a href="language.types.string.html" class="type string">string</a></span> to
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be evaluated or a <span class="type"><a href="language.types.boolean.html" class="type boolean">boolean</a></span> to be tested. In PHP 7, this may
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also be any expression that returns a value, which will be executed and
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the result used to indicate whether the assertion succeeded or failed.
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</p>
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</dd>
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<dt>
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<code class="parameter">description</code></dt>
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<dd>
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<p class="para">
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如果 <code class="parameter">assertion</code> 失败了，选项 description 将会包括在失败信息里。
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</p>
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</dd>
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<dt>
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<code class="parameter">exception</code></dt>
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<dd>
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<p class="para">
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In PHP 7, the second parameter can be a
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<strong class="classname">Throwable</strong> object instead of a descriptive
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<span class="type"><a href="language.types.string.html" class="type string">string</a></span>, in which case this is the object that will be
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thrown if the assertion fails and the
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<a href="info.configuration.html#ini.assert.exception" class="link">assert.exception</a>
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configuration directive is enabled.
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.assert-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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assertion 是 false 则返回 <strong><code>FALSE</code></strong>，否则是 <strong><code>TRUE</code></strong>。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.assert-changelog">
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<h3 class="title">更新日志</h3>
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<p class="para">
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<table class="doctable informaltable">
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<thead>
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<tr>
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<th>版本</th>
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<th>说明</th>
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</tr>
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</thead>
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<tbody class="tbody">
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<tr>
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<td>7.0.0</td>
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<td>
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<span class="function"><strong>assert()</strong></span> is now a language construct and not a
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function. <span class="function"><strong>assertion()</strong></span> can now be an expression.
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The second parameter is now interpreted either as an
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<code class="parameter">exception</code> (if a
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<strong class="classname">Throwable</strong> object is given), or as the
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<code class="parameter">description</code> supported from PHP 5.4.8 onwards.
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</td>
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</tr>
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<tr>
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<td>5.4.8</td>
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<td>
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增加了参数 <code class="parameter">description</code>。
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<code class="parameter">description</code> 现在也作为第四个参数提供给 <strong><code>ASSERT_CALLBACK</code></strong> 模式里的回调函数。
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</td>
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</tr>
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</tbody>
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</table>
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.assert-examples">
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<h3 class="title">范例</h3>
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<div class="refsect2 unknown-examplet" id="refsect2-function.assert-unknown-examplet">
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<h4 class="title">Traditional assertions (PHP 5 and 7)</h4>
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<p class="para">
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<div class="example" id="example-485">
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<p><strong>Example #1 使用自定义处理程序处理失败的断言</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// 激活断言，并设置它为 quiet<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_ACTIVE</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_WARNING</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_QUIET_EVAL</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//创建处理函数<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">my_assert_handler</span><span style="color: #007700">(</span><span style="color: #0000BB">$file</span><span style="color: #007700">, </span><span style="color: #0000BB">$line</span><span style="color: #007700">, </span><span style="color: #0000BB">$code</span><span style="color: #007700">)<br />{<br /> echo </span><span style="color: #DD0000">"<hr>Assertion Failed:<br /> File '</span><span style="color: #0000BB">$file</span><span style="color: #DD0000">'<br /><br /> Line '</span><span style="color: #0000BB">$line</span><span style="color: #DD0000">'<br /><br /> Code '</span><span style="color: #0000BB">$code</span><span style="color: #DD0000">'<br /><hr />"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// 设置回调函数<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_CALLBACK</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_assert_handler'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// 让一则断言失败<br /></span><span style="color: #0000BB">assert</span><span style="color: #007700">(</span><span style="color: #DD0000">'mysql_query("")'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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<div class="example" id="example-486">
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<p><strong>Example #2 使用自定义处理器打印描述信息</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// 激活断言，并设置它为 quiet<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_ACTIVE</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_WARNING</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_QUIET_EVAL</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//创建处理函数<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">my_assert_handler</span><span style="color: #007700">(</span><span style="color: #0000BB">$file</span><span style="color: #007700">, </span><span style="color: #0000BB">$line</span><span style="color: #007700">, </span><span style="color: #0000BB">$code</span><span style="color: #007700">, </span><span style="color: #0000BB">$desc </span><span style="color: #007700">= </span><span style="color: #0000BB">null</span><span style="color: #007700">)<br />{<br /> echo </span><span style="color: #DD0000">"Assertion failed at </span><span style="color: #0000BB">$file</span><span style="color: #DD0000">:</span><span style="color: #0000BB">$line</span><span style="color: #DD0000">: </span><span style="color: #0000BB">$code</span><span style="color: #DD0000">"</span><span style="color: #007700">;<br /> if (</span><span style="color: #0000BB">$desc</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">": </span><span style="color: #0000BB">$desc</span><span style="color: #DD0000">"</span><span style="color: #007700">;<br /> }<br /> echo </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// 设置回调函数<br /></span><span style="color: #0000BB">assert_options</span><span style="color: #007700">(</span><span style="color: #0000BB">ASSERT_CALLBACK</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_assert_handler'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Make an assertion that should fail<br /></span><span style="color: #0000BB">assert</span><span style="color: #007700">(</span><span style="color: #DD0000">'2 < 1'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">assert</span><span style="color: #007700">(</span><span style="color: #DD0000">'2 < 1'</span><span style="color: #007700">, </span><span style="color: #DD0000">'Two is less than one'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Assertion failed at test.php:21: 2 < 1
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Assertion failed at test.php:22: 2 < 1: Two is less than one
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect2 unknown-unknown-exampleu" id="refsect2-function.assert-unknown-unknown-exampleu">
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<h4 class="title">Expectations (PHP 7 only)</h4>
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<div class="example" id="example-487">
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<p><strong>Example #3 Expectations without a custom exception</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />assert</span><span style="color: #007700">(</span><span style="color: #0000BB">true </span><span style="color: #007700">== </span><span style="color: #0000BB">false</span><span style="color: #007700">);<br />echo </span><span style="color: #DD0000">'Hi!'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>
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With <a href="ini.core.html#ini.zend.assertions" class="link">zend.assertions</a> set to 0,
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the above example will output:
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</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Hi!
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</pre></div>
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</div>
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<div class="example-contents"><p>
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With <a href="ini.core.html#ini.zend.assertions" class="link">zend.assertions</a> set to 1
|
|
and <a href="info.configuration.html#ini.assert.exception" class="link">assert.exception</a> set to 0,
|
|
the above example will output:
|
|
</p></div>
|
|
<div class="example-contents screen">
|
|
<div class="cdata"><pre>
|
|
Warning: assert(): assert(true == false) failed in - on line 2
|
|
Hi!
|
|
</pre></div>
|
|
</div>
|
|
<div class="example-contents"><p>
|
|
With <a href="ini.core.html#ini.zend.assertions" class="link">zend.assertions</a> set to 1
|
|
and <a href="info.configuration.html#ini.assert.exception" class="link">assert.exception</a> set to 1,
|
|
the above example will output:
|
|
</p></div>
|
|
<div class="example-contents screen">
|
|
<div class="cdata"><pre>
|
|
Fatal error: Uncaught AssertionError: assert(true == false) in -:2
|
|
Stack trace:
|
|
#0 -(2): assert(false, 'assert(true == ...')
|
|
#1 {main}
|
|
thrown in - on line 2
|
|
</pre></div>
|
|
</div>
|
|
</div>
|
|
<div class="example" id="example-488">
|
|
<p><strong>Example #4 Expectations with a custom exception</strong></p>
|
|
<div class="example-contents">
|
|
<div class="phpcode"><pre><span style="color: #000000">
|
|
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">CustomError </span><span style="color: #007700">extends </span><span style="color: #0000BB">AssertionError </span><span style="color: #007700">{}<br /><br /></span><span style="color: #0000BB">assert</span><span style="color: #007700">(</span><span style="color: #0000BB">true </span><span style="color: #007700">== </span><span style="color: #0000BB">false</span><span style="color: #007700">, new </span><span style="color: #0000BB">CustomError</span><span style="color: #007700">(</span><span style="color: #DD0000">'True is not false!'</span><span style="color: #007700">));<br />echo </span><span style="color: #DD0000">'Hi!'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
|
|
</span>
|
|
</pre></div>
|
|
</div>
|
|
|
|
<div class="example-contents"><p>
|
|
With <a href="ini.core.html#ini.zend.assertions" class="link">zend.assertions</a> set to 0,
|
|
the above example will output:
|
|
</p></div>
|
|
<div class="example-contents screen">
|
|
<div class="cdata"><pre>
|
|
Hi!
|
|
</pre></div>
|
|
</div>
|
|
<div class="example-contents"><p>
|
|
With <a href="ini.core.html#ini.zend.assertions" class="link">zend.assertions</a> set to 1
|
|
and <a href="info.configuration.html#ini.assert.exception" class="link">assert.exception</a> set to 0,
|
|
the above example will output:
|
|
</p></div>
|
|
<div class="example-contents screen">
|
|
<div class="cdata"><pre>
|
|
Warning: assert(): CustomError: True is not false! in -:4
|
|
Stack trace:
|
|
#0 {main} failed in - on line 4
|
|
Hi!
|
|
</pre></div>
|
|
</div>
|
|
<div class="example-contents"><p>
|
|
With <a href="ini.core.html#ini.zend.assertions" class="link">zend.assertions</a> set to 1
|
|
and <a href="info.configuration.html#ini.assert.exception" class="link">assert.exception</a> set to 1,
|
|
the above example will output:
|
|
</p></div>
|
|
<div class="example-contents screen">
|
|
<div class="cdata"><pre>
|
|
Fatal error: Uncaught CustomError: True is not false! in -:4
|
|
Stack trace:
|
|
#0 {main}
|
|
thrown in - on line 4
|
|
</pre></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
|
|
<div class="refsect1 seealso" id="refsect1-function.assert-seealso">
|
|
<h3 class="title">参见</h3>
|
|
<p class="para">
|
|
<ul class="simplelist">
|
|
<li class="member"><span class="function"><a href="assert_options.html" class="function" rel="rdfs-seeAlso">assert_options()</a> - 设置/获取断言的各种标志</span></li>
|
|
</ul>
|
|
</p>
|
|
</div>
|
|
|
|
|
|
</div></div></div></body></html> |