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sprintf [C++ Reference]
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<h2><a name="sprintf" id="sprintf">sprintf</a></h2>
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<p>
Syntax:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="co2">#include <cstdio></span>
<span class="kw4">int</span> sprintf<span class="br0">(</span> <span class="kw4">char</span> <span class="sy0">*</span>buffer<span class="sy0">,</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy0">*</span>format<span class="sy0">,</span> ... <span class="br0">)</span><span class="sy0">;</span></pre>
<p>
The sprintf() function is just like printf(), except that the output is sent to
buffer. The return value is the number of characters written. For example:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="kw4">char</span> <span class="kw4">string</span><span class="br0">[</span>50<span class="br0">]</span><span class="sy0">;</span>
<span class="kw4">int</span> file_number <span class="sy0">=</span> <span class="nu0">0</span><span class="sy0">;</span>
sprintf<span class="br0">(</span> <span class="kw4">string</span><span class="sy0">,</span> <span class="st0">"file.%d"</span><span class="sy0">,</span> file_number <span class="br0">)</span><span class="sy0">;</span>
file_number<span class="sy0">++;</span>
output_file <span class="sy0">=</span> fopen<span class="br0">(</span> <span class="kw4">string</span><span class="sy0">,</span> <span class="st0">"w"</span> <span class="br0">)</span><span class="sy0">;</span></pre>
<p>
Note that sprintf() does the opposite of a function like atoi() – where atoi()
converts a string into a number, sprintf() can be used to convert a number into
a string.
For example, the following code uses sprintf() to convert an integer into a
string of characters:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="kw4">char</span> result<span class="br0">[</span>100<span class="br0">]</span><span class="sy0">;</span>
<span class="kw4">int</span> num <span class="sy0">=</span> <span class="nu0">24</span><span class="sy0">;</span>
sprintf<span class="br0">(</span> result<span class="sy0">,</span> <span class="st0">"%d"</span><span class="sy0">,</span> num <span class="br0">)</span><span class="sy0">;</span></pre>
<p>
This code is similar, except that it converts a floating-point number into an
array of characters:
</p>
<pre class="c code c++" style="font-family:monospace;"> <span class="kw4">char</span> result<span class="br0">[</span>100<span class="br0">]</span><span class="sy0">;</span>
<span class="kw4">float</span> fnum <span class="sy0">=</span> <span class="nu16">3.14159</span><span class="sy0">;</span>
sprintf<span class="br0">(</span> result<span class="sy0">,</span> <span class="st0">"%f"</span><span class="sy0">,</span> fnum <span class="br0">)</span><span class="sy0">;</span></pre>
<p>
Note that this function does not check the bounds of the buffer and therefore creates the risk of a buffer overflow.
A secure alternative is <a href="../../c/io/snprintf.html" class="wikilink1" title="c:io:snprintf">snprintf</a>
</p>
<p>
Related Topics: <a href="../../c/io/snprintf.html" class="wikilink1" title="c:io:snprintf">snprintf</a>, <a href="../../c/string/atof.html" class="wikilink1" title="c:string:atof">atof</a>, <a href="../../c/string/atoi.html" class="wikilink1" title="c:string:atoi">atoi</a>, <a href="../../c/string/atol.html" class="wikilink1" title="c:string:atol">atol</a>, <a href="../../c/io/fprintf.html" class="wikilink1" title="c:io:fprintf">fprintf</a>, <a href="../../c/io/printf.html" class="wikilink1" title="c:io:printf">printf</a>
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