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- <h2><a name="atoi" id="atoi">atoi</a></h2>
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- Syntax:
- </p>
- <pre class="c code c++" style="font-family:monospace;"> <span class="co2">#include <cstdlib></span>
- <span class="kw4">int</span> atoi<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy0">*</span>str <span class="br0">)</span><span class="sy0">;</span></pre>
- <p>
- The atoi function converts <code>str</code> into an integer, and returns that integer. <code>str</code>
- should start with whitespace or some sort of number, and atoi will stop
- reading from <code>str</code> as soon as a non-numerical character has been read. For
- example:
- </p>
- <pre class="c code c++" style="font-family:monospace;"> <span class="kw4">int</span> i<span class="sy0">;</span>
- i <span class="sy0">=</span> atoi<span class="br0">(</span> <span class="st0">"512"</span> <span class="br0">)</span><span class="sy0">;</span>
- i <span class="sy0">=</span> atoi<span class="br0">(</span> <span class="st0">"512.035"</span> <span class="br0">)</span><span class="sy0">;</span>
- i <span class="sy0">=</span> atoi<span class="br0">(</span> <span class="st0">" 512.035"</span> <span class="br0">)</span><span class="sy0">;</span>
- i <span class="sy0">=</span> atoi<span class="br0">(</span> <span class="st0">" 512+34"</span> <span class="br0">)</span><span class="sy0">;</span>
- i <span class="sy0">=</span> atoi<span class="br0">(</span> <span class="st0">" 512 bottles of beer on the wall"</span> <span class="br0">)</span><span class="sy0">;</span></pre>
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- All five of the above assignments to the variable <code>i</code> would result in it being
- set to 512.
- </p>
- <p>
- If the conversion cannot be performed, then atoi will return zero:
- </p>
- <pre class="c code c++" style="font-family:monospace;"> <span class="kw4">int</span> i <span class="sy0">=</span> atoi<span class="br0">(</span> <span class="st0">" does not work: 512"</span> <span class="br0">)</span><span class="sy0">;</span> <span class="co1">// results in i == 0</span></pre>
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- You can use <a href="../../c/io/sprintf.html" class="wikilink1" title="c:io:sprintf">sprintf</a> to convert a number into a string.
- </p>
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- Related Topics: <a href="../../c/string/atof.html" class="wikilink1" title="c:string:atof">atof</a>, <a href="../../c/string/atol.html" class="wikilink1" title="c:string:atol">atol</a>, <a href="../../c/io/sprintf.html" class="wikilink1" title="c:io:sprintf">sprintf</a>
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