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<h1 class='fqn'><span class='in-band'>Macro <a href='index.html'>std</a>::<wbr><a class="macro" href=''>line</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'>
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</span><a class='srclink' href='../src/std/macros.rs.html#481' title='goto source code'>[src]</a></span></h1>
<pre class="rust macro">
<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">line</span> {
() <span class="op">=></span> { ... };
}</pre>
<div class='docblock'><p>A macro which expands to the line number on which it was invoked.</p>
<p>With <a href="macro.column.html"><code>column!</code></a> and <a href="macro.file.html"><code>file!</code></a>, these macros provide debugging information for
developers about the location within the source.</p>
<p>The expanded expression has type <code>u32</code> and is 1-based, so the first line
in each file evaluates to 1, the second to 2, etc. This is consistent
with error messages by common compilers or popular editors.
The returned line is not the invocation of the <code>line!</code> macro itself,
but rather the first macro invocation leading up to the invocation
of the <code>line!</code> macro.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">current_line</span> <span class="op">=</span> <span class="macro">line</span><span class="macro">!</span>();
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"defined on line: {}"</span>, <span class="ident">current_line</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Alet%20current_line%20%3D%20line!()%3B%0Aprintln!(%22defined%20on%20line%3A%20%7B%7D%22%2C%20current_line)%3B%0A%7D">Run</a></pre>
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