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<title>static functions</title>
<head>
<script language="JavaScript">
</script>
</head>
<body bgcolor="#ffffcc">
<hr>
<center>
<h1>static functions</h1>
</center>
<hr>
<p>
<b>static functions</b> are functions that are only visable to other
functions in the same file. Consider the following code.
<p>
<table border=2 bgcolor=ivory align=left>
<th>
main.c
</th>
<tr>
<td>
<pre>
#include <stdio.h>
main()
{
Func1();
Func2();
}
</pre>
</td>
</tr>
</table>
<table border=2 bgcolor=ivory>
<th>
funcs.c
</th>
<tr>
<td>
<pre>
/*************************************
*
* Function declarations (prototypes).
*
*************************************/
/* Func1 is only visable to functions in this file. */
<font color=red><i>static</i></font> void Func1(void);
/* Func2 is visable to all functions. */
void Func2(void);
/*************************************
*
* Function definitions
*
*************************************/
void Func1(void)
{
puts("Func1 called");
}
/*************************************/
void Func2(void)
{
puts("Func2 called");
}
</pre>
</td>
</tr>
</table>
<p>
If you attempted to compile this code with the following
command,
<p>
<center>
<table border=2 bgcolor=ivory>
<tr>
<td>
<pre>
gcc main.c funcs.c
</pre>
</td>
</tr>
</table>
</center>
<p>
it will fail with an error simular to.....
<p>
<center>
<table border=2 bgcolor=ivory>
<tr>
<td>
<pre>
undefined reference to `Func1'
</pre>
</td>
</tr>
</table>
</center>
<p>
Because 'Func1' is declared as <font color=red><i>static</i></font>
and cannot be 'seen' by 'main.c'.
<p>
<hr>
<h2>Notes:</h2>
For some reason, <font color=red><i>static</i></font> has different
meanings in in different contexts.
<ol>
<li> When specified on a function declaration, it makes the
function local to the file.
<p>
<li> When specified with a variable inside a function, it
allows the vairable to retain its value between calls to
the function. See
<a href=../CONCEPT/storage_class.html#static>static variables</a>.
</ol>
It seems a little strange that the same keyword has such
different meanings....
<p>
<hr>
<h2>See Also:</h2>
<img src="../../GRAPHICS/whiteball.gif">
<a href="../CONCEPT/storage_class.html#static">static variables</a><p>
<font color=brown>
<img src="../../GRAPHICS/whiteball.gif">
<a href="../../CPLUSPLUS/SYNTAX/static.htm">C++ extensions for </a>static<p>
</font>
<p>
<hr>
<p>
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<td width="25%">
<a href="../cref.html"> Top</a>
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<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>
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</table>
</center>
<p>
<hr>
<address>Martin Leslie
</address><p>
</body>
</html>
|
