<title>The sizeof operator</title>
<head>
<script language="JavaScript">
</script>
</head>
<body bgcolor="#ffffcc">
<hr>
<center>
<h1>The sizeof operator</h1>
</center>
<hr>
<p>
<b>sizeof</b> will return the number of bytes reserved for a variable or
<a href="../CONCEPT/data_types.html">data type</a>.
<p>
The following code shows <b>sizeof</b> returning the length of a data type.
<p>
<table border=2 width="100%" bgcolor=ivory>
<tr>
<td>
<pre>
/* How big is an int? expect an answer of 4. */
main()
{
printf("%d \n", sizeof(int));
}
</pre>
</td>
</tr>
</table>
<p>
<b>sizeof</b> will also return the number of bytes reserved for a
<a href="struct.html">structure</a>.
<p>
<table border=2 width="100%" bgcolor=ivory>
<tr>
<td>
<pre>
/* Will print 8 on most machines. */
main()
{
struct
{
int a;
int b;
} TwoInts;
printf("%d \n", sizeof(TwoInts));
}
</pre>
</td>
</tr>
</table>
<p>
Finally, <b>sizeof</b> will return the length of a variable.
<p>
<table border=2 width="100%" bgcolor=ivory>
<tr>
<td>
<pre>
main()
{
char String[20];
printf ("%d \n", sizeof String);
printf ("%d \n", sizeof (String));
}
</pre>
</td>
</tr>
</table>
<p>
In the example above I have printed the size of 'String' twice. This is to
show that when dealing with variables, the brackets are optional.
I recommend that you always place the brackets around the sizeof argument.
<p>
<hr>
<h2>Examples:</h2>
<a href="../EXAMPLES/sizeof.c">Example 1</a> Data types.
<p>
<a href="../EXAMPLES/sizeof1.c">Example 2</a> Data objects.
<p>
<hr>
<h2>See also:</h2>
<img src="../../GRAPHICS/whiteball.gif">
The <a href="../FUNCTIONS/strlen.html">strlen </a>function.
<p>
<img src="../../GRAPHICS/whiteball.gif">
Other <a href="../CONCEPT/expressions.html">operators</a>
<p>
<img src="../../GRAPHICS/whiteball.gif">
<a href="../FUNCTIONS/malloc.html">malloc</a> function.
<p>
<hr>
<p>
<center>
<table border=2 width="80%" bgcolor="ivory">
<tr align=center>
<td width="25%">
<a href="../cref.html"> Top</a>
</td><td width="25%">
<a href="../master_index.html"> Master Index</a>
</td><td width="25%">
<a href="keywords.html"> Keywords</a>
</td><td width="25%">
<a href="../FUNCTIONS/funcref.htm"> Functions</a>
</td>
</tr>
</table>
</center>
<p>
<hr>
<address>Martin Leslie
</address><p>
</body>
</html>