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<html>
<head>
<title>Function Overloading.</title>
</head>
<body bgcolor="#dddddd">
<font color=brown>
<hr>
<center><h1>Function Overloading.</h1></center>
<hr>
<p>
Overloading is a technique that allows you to give a several
functions with the same name but different parameter lists.
<p>
Consider the following program.
<p>
<center>
<table border=1 width="80%" bgcolor="ivory">
<tr>
<td>
<pre>
#include <iostream.h>
void Add(int Left, int Right);
main ()
{
Add(5, 9); // Integer Add.
Add(3.2, 7.1); // Floating point Add.
}
// Integer version of Add.
void Add(int Left, int Right)
{
cout << Left << " + " << Right << " = " << Left+Right << endl;
}
</pre>
</td>
</tr>
</table>
</center>
<p>
The program contains the <b>Add</b> function that adds integers.
But the main calls it twice, once passing integers and the second
time passing floating point numbers. The program will compile and run
but you will get incorrect results because the floats will be
<a href=../../C/CONCEPT/cast.html> cast</a> to integers.
<p>
The second
program offers a solution by <b>overloading</b> the <b>Add</b> function.
<p>
<center>
<table border=1 width="80%" bgcolor="ivory">
<tr>
<td>
<pre>
#include <iostream.h>
void Add(int Left, int Right);
<b>void Add(double Left, double Right);</b>
main ()
{
Add(5, 9); // Integer Add.
Add(3.2, 7.1); // Floating point Add.
}
// Integer version of Add.
void Add(int Left, int Right)
{
cout << Left << " + " << Right << " = " << Left+Right << endl;
}
<b>
// float version of Add.
void Add(double Left, double Right)
{
cout << Left << " + " << Right << " = " << Left+Right << endl;
}
</b>
</pre>
</td>
</tr>
</table>
</center>
The compiler can now look at the call list and match it with
a function with the correct parameter list and the floating
point addition is performed correctly.
<p>
Please note that the returned argument is not used when matching
overloaded functions.
<hr>
<h2>Examples:</h2>
<img src="../../GRAPHICS/computer.gif" alt="o">
<a href="../EXAMPLES/overload.cc">Example program.</a>
<p>
<hr>
<h2>See Also:</h2>
<img src="../../GRAPHICS/whiteball.gif" alt="o">
<a href="fundefault.html">Default Parameter Values.</a>.
</font>
<hr>
<font color=black>
<h2>C References</h2>
<p>
<img src="../../GRAPHICS/whiteball.gif" alt="o">
<a href="../../C/SYNTAX/functions.html">Function Basics</a>.
</font>
<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="../../C/master_index.html">Master Index</a>
</td><td width="25%">
<a href="../SYNTAX/keywords.html">Keywords</a>
</td><td width="25%">
<a href="../../C/FUNCTIONS/funcref.htm">Functions</a>
</td>
</tr>
</table>
</center>
<p>
<hr>
<font color=brown>
<address>Martin Leslie
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</body>
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