valid-number.md

<p>Validate if a given string can be interpreted as&nbsp;a decimal number.</p>

<p>Some examples:<br />
<code>&quot;0&quot;</code> =&gt; <code>true</code><br />
<code>&quot; 0.1 &quot;</code> =&gt; <code>true</code><br />
<code>&quot;abc&quot;</code> =&gt; <code>false</code><br />
<code>&quot;1 a&quot;</code> =&gt; <code>false</code><br />
<code>&quot;2e10&quot;</code> =&gt; <code>true</code><br />
<code>&quot; -90e3&nbsp; &nbsp;&quot;</code> =&gt; <code>true</code><br />
<code>&quot; 1e&quot;</code> =&gt; <code>false</code><br />
<code>&quot;e3&quot;</code> =&gt; <code>false</code><br />
<code>&quot; 6e-1&quot;</code> =&gt; <code>true</code><br />
<code>&quot; 99e2.5&nbsp;&quot;</code> =&gt; <code>false</code><br />
<code>&quot;53.5e93&quot;</code> =&gt; <code>true</code><br />
<code>&quot; --6 &quot;</code> =&gt; <code>false</code><br />
<code>&quot;-+3&quot;</code> =&gt; <code>false</code><br />
<code>&quot;95a54e53&quot;</code> =&gt; <code>false</code></p>

<p><strong>Note:</strong> It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one. However, here is a list of characters that can be in a valid decimal number:</p>

<ul>
	<li>Numbers 0-9</li>
	<li>Exponent - &quot;e&quot;</li>
	<li>Positive/negative sign - &quot;+&quot;/&quot;-&quot;</li>
	<li>Decimal point - &quot;.&quot;</li>
</ul>

<p>Of course, the context of these characters also matters in the input.</p>

<p><strong>Update (2015-02-10):</strong><br />
The signature of the <code>C++</code> function had been updated. If you still see your function signature accepts a <code>const char *</code> argument, please click the reload button to reset your code definition.</p>