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<html>
<head>
<title>EAGLE Help: Function Definitions</title>
</head>
<body bgcolor=white>
<font face=Helvetica,Arial>
<hr>
<i>EAGLE Help</i>
<h1><center>Function Definitions</center></h1>
<hr>
You can write your own User Language functions and call them just like the
<a href=230.htm>Builtin Functions</a>.
<p>
The general syntax of a <i>function definition</i> is
<pre>
type identifier(parameters)
{
statements
}
</pre>
where <tt>type</tt> is one of the
<a href=154.htm>data</a> or
<a href=161.htm>object types</a>,
<tt>identifier</tt> is the name of the function,
<tt>parameters</tt> is a list of comma separated parameter definitions,
and <tt>statements</tt> is a sequence of <a href=215.htm>statements</a>.
<p>
Functions that do not return a value have the type <tt>void</tt>.
<p>
A function must be defined <b>before</b> it can be called, and function
calls can not be recursive (a function cannot call itself).
<p>
The statements in the function body may modify the values of the parameters,
but this will not have any effect on the arguments of the
<a href=214.htm>function call</a>.
<p>
Execution of a function can be terminated by the
<tt><a href=224.htm>return</a></tt> statement. Without any
<tt>return</tt> statement the function body is executed until it's closing
brace (<tt>}</tt>).
<p>
A call to the <tt><a href=247.htm>exit()</a></tt> function will
terminate the entire User Language Program.
<p>
<b>The special function <tt>main()</tt></b>
<p>
If your User Language Program contains a function called
<tt>main()</tt>, that function will be explicitly called as the
main function, and it's return value will be the
<a href=130.htm>return value</a> of the program.
<p>
Command line arguments are available to the program through the global
<a href=229.htm>Builtin Variables</a> <tt>argc</tt> and <tt>argv</tt>.
<p>
<b>Example</b>
<pre>
int CountDots(string s)
{
int dots = 0;
for (int i = 0; s[i]; ++i)
if (s[i] == '.')
++dots;
return dots;
}
string dotted = "This.has.dots...";
output("test") {
printf("Number of dots: %d\n",
CountDots(dotted));
}
</pre>
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