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| author | Tobias Klauser <tklauser@distanz.ch> | 2008-01-27 11:37:44 +0100 |
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| committer | Tobias Klauser <tklauser@xenon.tklauser.home> | 2008-01-27 11:37:44 +0100 |
| commit | 7e0f021a9aec35fd8e6725e87e3313b101d26f5e (patch) | |
| tree | b1cacc4b24393f517aeb4610e9e1021f954307a8 /reference/CPLUSPLUS/SYNTAX/class.html | |
Initial import (2.0.2-6)2.0.2-6
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| -rw-r--r-- | reference/CPLUSPLUS/SYNTAX/class.html | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/reference/CPLUSPLUS/SYNTAX/class.html b/reference/CPLUSPLUS/SYNTAX/class.html new file mode 100644 index 0000000..45ec2af --- /dev/null +++ b/reference/CPLUSPLUS/SYNTAX/class.html @@ -0,0 +1,185 @@ +<title>CLASS keyword</title> +<!-- Changed by: Martin Leslie, 14-Mar-1996 --> +<body bgcolor=#dddddd> +<font color=brown> +<hr> +<center><h1>class keyword</h1></center> +<hr> +<p> +The concept of a class +allows you to +<a href=../../C/glossary.html#encapsulation>encapsulate</a> + a set of related variables and only +allow access to them via predetermined functions. +<p> + +The <b>class</b> keyword is used to declare the group of variables +and functions and the visability of the variables and functions. +Here is a basic example. + +<p> +<center> +<table width="80%" border="1" bgcolor="ivory"> +<tr> +<td> +<pre> + + class String + { + public: + + void Set(char *InputStr) // Declare an Access function + { + strcpy(Str, InputStr); + } + + private: + + char Str[80]; // Declare a hidden variable. + + }; +</pre> +</td> +</tr> +</table> +</center> +<p> + +<ul> +<li><b>private:</b> means that all variables and functions that + follow are only visable from within the class. + +<li><b>public:</b> all functions and variables that follow this + statement can be accessed from outside the class. +</ul> + +Now we have declared a class called <b>String</b> we need to +use it. +<p> +<center> +<table width="80%" border="1" bgcolor="ivory"> +<tr> +<td> +<pre> + + main() + { + String Title; + + Title.Set("My First Masterpiece."); + } +</pre> +</td> +</tr> +</table> +</center> +<p> + +This code creates a String +<a href=../../C/glossary.html#class_object>object</a> +called Title and then uses the <b>Set</b> member function +to initialise the value of <b>Str</b>. +<p> +In C++ the member function <b>Set</b> is also known as a +<a href=../../C/glossary.html#method>method</a> +<p> +This is the strength +of object oriented programming, the ONLY way to change +<b>Str</b> is via the <b>Set</b> method. + +<p> + +The final code example brings the last two examples together +ands a new method (called Get) that shows the contents of +<b>Str</b> + +<p> +<center> +<table width="80%" border="1" bgcolor="ivory"> +<tr> +<td> +<pre> + + #include <stdlib.h> + #include <iostream.h> // Instead of stdio.h + + class String + { + public: + + void Set(char *InputStr) // Declare an Access function + { + strcpy(Str, InputStr); + } + <b> + char *Get(void) // Declare an Access function + { + return(Str); + } + </b> + + private: + + char Str[80]; // Declare a hidden variable. + + }; + + main() + { + String Title; + + Title.Set("My First Masterpiece."); + + <b>cout << Title.Get() << endl;</b> + } +</pre> +</td> +</tr> +</table> +</center> +<p> + + +<hr> +<h2>Examples:</h2> +<img src="../../GRAPHICS/computer.gif"> +<a href="../EXAMPLES/class1.cc">Example program.</a> +<hr> +<h2>See Also:</h2> + +<img src="../../GRAPHICS/whiteball.gif"> +<a href="../CONCEPT/constructor.html">Constructors and destructors.</a> +<p> +<img src="../../GRAPHICS/whiteball.gif"> +<a href="../CONCEPT/inheritance.html">Class Inheritance.</a> +<hr> + +</font> +<font color=black> +<h2>C References</h2> +<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="../../C/master_index.html">Master Index</a> +</td><td width="25%"> +<a href="keywords.html">C++ 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 +08-Feb-96</address><p> +</font> + |