updated

LDP/howto/linuxdoc/C++Programming-HOWTO.sgml

@@ -40,7 +40,7 @@ C++ Programming HOW-TO
 <author>Al Dev (Alavoor Vasudevan) 
        <htmlurl url="mailto:alavoor@yahoo.com"
              name="alavoor@yahoo.com">
-<date>v8.0, 26 April 2000
+<date>v9.0, 31 May 2000
 <abstract>
 This document discusses methods to avoid memory problems in C++ and 
 also will help you to program properly in C++ language. 
@@ -71,8 +71,12 @@ means almost all the operating systems on this planet!).
 <p>
 C++ is the most popular language and will be used for a long time in the future
 inspite of emergence of Java. C++ runs <bf>extremely fast</bf> and is 
-in fact <bf> 20 to 30 times FASTER than </bf> Java. Java runs very slow 
-because it is an byte-code-interpreted language running on top of "virtual engine". The 
+in fact <bf> 10 to 20 times FASTER than </bf> Java. Java runs very slow 
+because it is an byte-code-interpreted language running on top of "virtual engine". 
+Java runs faster with JIT compiler but is still slower than C++. And optimized 
+C++ program is 
+about <bf>3 to 4 times faster</bf> than Java 
+using the JIT (Just-In-Time) compiler!! The 
 memory management in Java is automated, so that programmers do not directly
 deal with memory allocations. This document attempts
 to automate the memory management in C++ to make it much more easy to use.
@@ -104,7 +108,8 @@ to usage of features like -
 
 The usage of <bf>char *</bf> and <bf>strcpy</bf> causes <it>horrible</it> memory 
 problems due to <it>"overflow"</it>, 
-<it>"fence past errors"</it> or  <it>"memory leaks"</it>.
+<it>"fence past errors"</it>, <it>"step-on-others-toe"</it> 
+(hurting other variable's memory locations) or  <it>"memory leaks"</it>.
 The memory problems are extremely hard to debug and are 
 very time consuming to fix and trouble-shoot. Memory problems bring down
 the productivity of programmers. This document helps in increasing the
@@ -114,12 +119,12 @@ Memory related bugs are very tough to crack, and even experienced programmers
 take several days, weeks or months to debug memory related problems. Many times memory 
 bugs will be "hiding" in the code for several months and can cause unexpected
 program crashes!! The usage of 
-<bf>char *</bf> 
+<bf>char *</bf> in C++  
 is costing USA and Japan $2 billion 
 every year in time lost in debugging and downtime of programs. If you use
 <bf>char *</bf> 
 in C++ then it is a very costly affair especially if your programs have more
-than a million lines of code.
+than 50,000 lines of code.
 
 Hence, the following techniques are proposed to overcome the faults of "C"
 language.
@@ -134,7 +139,24 @@ The datatypes like char *, char[] and functions like strcpy, strcat
 are <bf>evil</bf> and must be completetly <bf>BANNED</bf> from usage in C++!!
 The
 <bf>"char *"</bf>
-is like <it>smallpox virus</it> and it must be eradicated from this world!!
+is like <it>smallpox virus</it> and it must be eradicated from C++ world!!
+If you want to use "char *" as in some system functions than you 
+should use "C" language. You would put 
+all your "C" programs in a seperate file and link to "C++" programs using 
+the <it>linkage-specification</it> statement <bf>extern "C" </bf> -
+<code>
+extern "C" {
+#include <stdlib.h>
+}
+
+extern "C" {
+	comp();
+	some_c_function();
+}
+</code>
+The <bf>extern "C"</bf> statement says that everything within the 
+brace-surrounded block - in this case, everything in the header file 
+and comp(), some_c_function() is compiled by a C compiler.
 
 Instead of using char * and char[] all the C++ programmers MUST use the 
 <bf>'mychar class'</bf> 
@@ -189,7 +211,15 @@ It is recommended you do programming in object-oriented "C++" for all your
 application programming or general purpose programming. You can take full
 advantage of object oriented facilities of C++. The C++ compiler is lot
 more complex than "C" compiler and C++ programs may run bit slower than "C"
-programs. But compiler optimizer options like -O or -O3 can speed up C++.
+programs. But speed difference between "C" and "C++" is very minute - it 
+could be few milli-seconds which may have little impact 
+for real-time programming.
+Since computer hardware is becoming cheaper and faster and memory
+'RAM' is getting faster and cheaper, it is worth doing code in C++ rather than
+"C" as time saved in clarity and re-usability of C++ code 
+offsets the slow speed.
+Compiler optimizer options like -O or -O3 can speed up C++/C
+which is not available in Java.
 
 Nowadays, "C" language is primarily used for "systems programming" to develop
 operating sytems, device drivers etc..
@@ -201,7 +231,14 @@ XML to get better performance. Hence, the golden rule is <it>"Web-server side pr
 use C++ and web-client side (browser) programming use Java applets"</it>. The 
 reason is - the server-side OS is under your control and never changes and you
 will never know what the client side web-browser OS is. It can be Windows 95/98/NT/2000
-or Linux, Apple Mac, OS/2, Solaris etc..
+or Linux, Apple Mac, OS/2, Netware, Solaris etc..
+
+The greatness of Java is that it can run "GUI Applets" on any OS platform!
+Java was created to replace the Microsoft Windows 95/NT GUI clients.
+In other words - "Java is the Windows-GUI system of next century". Java 
+is already embedded in web-browsers like Netscape, Hot Java, etc..
+
+Hence, Java runs on "client" and C++ runs on servers!!
 <!--
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@@ -489,6 +526,10 @@ For an example, see the file "mychar.h" which is using
 the 
 <ref id="my_malloc" name="my_malloc()">
 and my_free() functions.
+
+<bf>WARNING :</bf> Do not use free() to free memory allocated with 'new'
+or 'delete' to free memory allocated with malloc. If you do, then
+results will be unpredictable!!
 <!-- 
 	*******************************************
 	************ End of Section ***************
@@ -501,15 +542,18 @@ and my_free() functions.
 -->
 <sect> Pointers are problems <label id="pointers">
 <p>
+Pointers are not required for general purpose programming. In modern
+languages like Java there is no support for pointers!! Pointers make
+the programs messy and programs using pointers are very hard to read.
+
+Avoid using pointers as much as possible and use references. Pointers are really a
+great pain. It is possible to write a application without using pointers.
+
 A <bf>reference</bf> is an alias; when you create a reference, you initialize
 it with the name of another object, the target. From the moment on, the reference
 acts as an alternative name of the target, and anything you do to the reference
 is really done to the target.
 
-Avoid using pointers as much as possible and use references. Pointers are really a
-great pain. It is possible to write a application without using pointers.
-In languages like Java, pointers are not supported at all !!
-
 <bf>Syntax of References:</bf> Declare a reference by writing the type, followed by
 the reference operator (&), followed by the reference name. References
 <bf>MUST</bf> be initialized at the time of creation.
@@ -897,6 +941,8 @@ Additional requests are - you must retain the author's name, email address
 and this copyright notice on all the copies. If you make any changes 
 or additions to this document then you please 
 intimate all the authors of this document.
+Brand names mentioned in this document are property of their respective 
+owners.
 <!-- 
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 	************ End of Section ***************

LDP/howto/linuxdoc/HOWTO-INDEX.sgml

@@ -187,7 +187,7 @@ device parameters.
 How to install, configure and use a busmouse under Linux.
 
 <item><htmlurl url="C++Programming-HOWTO.html" name="C++Programming-HOWTO">,
-<BF/C++ Programming HOWTO/ <p><em/Updated: April 2000/.
+<BF/C++ Programming HOWTO/ <p><em/Updated: May 2000/.
 Discusses methods to avoid memory problems in C++ and
 also will help you to program properly in C++ language.
 Applies to all operating sytems.