Platform independence/relevance understanding

Origin:

Let's talk about it first. Today, I suddenly thought of this topic because I recently read the format instructions in the PDF document, which mentioned: device-independent (platform independence ), I want to extract the titles in each small file from a bunch of PDF documents to make a directory (I am too lazy to copy it. I originally found a Perl module on CPAN. I won't install it in tgz format ~~~ If you pass by, teach me ).

The language skills are not good. I am confused by a bunch of tricks. The question is as follows:

I. As mentioned above, the PDF format is device-independent (platform-independent). In order to achieve this platform-independent,

Two steps are required:

1. Use a specific tool (which should be the software for making PDF files) to create a platform-independent PDF document. (Encoding ?)

2. Another tool (PDF reading software) is used to output the platform-independent PDF documents to the platform, for example, displayed on the screen or printed. (Decoding ?)

In this case, I understand that the so-called platform independence is prerequisite and relative, that is, there is no real platform independence.

2. Now I understand the platform independence:

1. A literal understanding of platform independence means that this program, or tools, can run on any platform.

2. In order to make your software platform irrelevant, you have to make another tool to parse it on different platforms.

3. Therefore, the platform has nothing to do with. You need a tool that deals with the underlying platform (for example, the Java Virtual Machine-but the installation packages of each platform of the Java Virtual Machine itself are different, Khan ~~~), If you have another platform, this tool should be modified once more, and then you can use this tool to parse your software in the agreed format, then your upper-layer, of course, seems to have nothing to do with the platform.

Postscript:

I can't understand it any more. I found that if I went deeper, it seemed that I had to fall into the problem of having a chicken first or having an egg first.

Statement:This is my personal opinion. Do not be misled by me. ^_^

Retained the following information:
Author (author): smilelance
Time: 2006.12.15
Source (from): http://blog.csdn.net/smilelance