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| author | Tobias Klauser <tklauser@distanz.ch> | 2008-01-27 11:37:44 +0100 |
|---|---|---|
| committer | Tobias Klauser <tklauser@xenon.tklauser.home> | 2008-01-27 11:37:44 +0100 |
| commit | 7e0f021a9aec35fd8e6725e87e3313b101d26f5e (patch) | |
| tree | b1cacc4b24393f517aeb4610e9e1021f954307a8 /reference/CPLUSPLUS/CONCEPT/fundefault.html | |
Initial import (2.0.2-6)2.0.2-6
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| -rw-r--r-- | reference/CPLUSPLUS/CONCEPT/fundefault.html | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/reference/CPLUSPLUS/CONCEPT/fundefault.html b/reference/CPLUSPLUS/CONCEPT/fundefault.html new file mode 100644 index 0000000..80cd0aa --- /dev/null +++ b/reference/CPLUSPLUS/CONCEPT/fundefault.html @@ -0,0 +1,115 @@ +<html> +<head> +<title>Default Parameters.</title> +</head> +<body bgcolor="#dddddd"> +<font color=brown> +<hr> +<center><h1>Default Parameters.</h1></center> +<hr> +<p> +Within C you could not provide default values for function +parameters. Well, C++ has come to your rescue. +<p> + +<center> +<table border="1" width="80%" bgcolor="ivory"> +<tr> +<td> +<pre> + + #include <iostream.h> + + void Func( int one, <b>int two=2, int three=3</b>); + + main () + { + Func(10, 20, 30); + Func<b>(10, 20); // Let the last parm default</b> + Func<b>(10); // Just provide the required parm.</b> + } + + + void Func( int one, int two, int three) + { + cout << "One = " << one << endl; + cout << "Two = " << two << endl; + cout << "Three = " << three << endl << endl; + } +</pre> +</td> +</tr> +</table> +</center> + +<p> +From this example, you can see that the prototype/function declaration +gives default values for the second and third parameters. It is now +down to the programmer calling the function to decide how many +s/he wants to provide. +<p> +There are some basic rules that should be applied when using +default parameter values. +<ul> +<li>When a default is provided, all remaining parameters must be + given defaults. There can not be any holes. +<li>Default values must be of the correct type. +<li>Defaults can be placed on the function prototype or the function + definition. They can also be placed in both locations at the + same time. I have been told its good practice to place them + in the prototype only. +</ul> +<p> +<hr> +<h2>Examples:</h2> +<!-- +<img src="../../GRAPHICS/computer.gif" alt="o"> +<a href="../EXAMPLES/xxxx.cc">Example program.</a> +<p> +--> + +<hr> +<h2>See Also:</h2> + +<img src="../../GRAPHICS/whiteball.gif" alt="o"> +<a href="funcoverload.html">Function Name Overloading</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 +<script language="JavaScript"> +<!-- // +document.write(document.lastModified); +// --> +</script> +</address><p> +</font> +</body> +</html> |