Eight Bit Byte Mac OS
Most likely, your input file uses a single-byte 8-bit encoding such as ISO-8859-1, frequently used to encode 'Western European' languages. Regardless of the actual market share, the most compatible version (across operating systems) of IE was 5.x, which had Mac OS 9 and Mac OS X, Unix, and most Windows versions available and supported for a short period in the late 1990s (although 4.x had a more unified codebase across versions). Assuming Snow Leopard (Mac OS X 10.6.2 - Intel), then 'long' is 64-bits with the default compiler. Specify 'g -m64' and it will likely be 64-bits on earlier versions too. How a particular host (processor, OS, etc.) handles the byte and bit order is off-topic here. In general, programming libraries handle the problem for your particular host, but that, too, is off-topic here, and you could try to ask about the programming aspect on Stack Overflow.
Table Of Content
1- Bit
I start the story by talking about base-10 system. When you understand the base-10 system, our story will not be interrupted and confused.
Okay, the base-10 system is the most popular one but it's not unique. Many cultures used different systems in the past, however, today most of them have moved to base-10 system. The base-10 system uses 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, which are put together to form another number.
If you only have one box, you can only write a number from 0 to 9. But ..- If you have two boxes, you can write a number from 0 to 99.
- If you have three boxes, you can write a number from 0 to 999.
All boxes from right to left have a factor which is in turn 10^0, 10^1, 10^2, ...
BIT
BIT is short for Binary digIT (information unit). A bit that denotes value 0 or 1, is called the smallest unit in the computer. 0, 1 are two basic digits of base-2 system.
Let infer as base-10 system and apply it to base-2 system. If you have one box, you can write 2 numbers such as 0 and 1. If you have 2 boxes, you can write 4 numbers such as 00, 01, 10, and 11 (Note: Do not be mistaken, these numbers are ones of base-2 system).
For base-2 system, the boxes from right to left have 1 factor. They are in turn 2^0, 2^1, 2^2, ...
The following image describes the way how to convert a number of base-2 system to base-10 system.
Thus:- If you have two boxes in the base-2 system, you can write the largest number of 11 (base-2), which is equivalent to 3 in the base-10 system.
- If you have 3 boxes in base-2 system, you can write the largest number of 111 (base-2), which is equivalent to 7 in base -10 system.
| Box Numbers | Maximum Number (Base-2) | Convert to Base-10 |
| 1 | 1 | 1 (2^1 - 1) |
| 2 | 11 | 3 (2^2 - 1) |
| 3 | 111 | 7 (2^3 - 1) |
| 4 | 1111 | 15 (2^4 - 1) |
| 5 | 11111 | 31 (2^5 - 1) |
| 6 | 111111 | 63 (2^6 - 1) |
| 7 | 1111111 | 127 (2^7 - 1) |
| 8 | 11111111 | 255 (2^8 - 1) |
| 9 | 111111111 | 511 (2^9 - 1) |
Why does the computer use base-2 system but not base-10 system?
You surely ask the question 'Why does computer use base-2 system but not base-10 system?'. I have asked this question before, like you.
Computers operate by using millions of electronic switches (transistors), each of which is either on or off (similar to a light switch, but much smaller). The state of the switch (either on or off) can represent binary information, such as yes or no, true or false, 1 or 0. The basic unit of information in a computer is thus the binary digit (BIT). Although computers can represent an incredible variety of information, every representation must finally be reduced to on and off states of a transistor.
Thus, the answer is that computer does not have many states to store information, therefore, it stores information based on the two states of ON and OFF (1 and 0 respectively).
Your computer hard drive also stores data on the principle of 0, 1. It includes recorders and readers. It has one or more disks, which are coated with a magnetic layer of nickel. Magnetic particles can have south-north direction or north-south direction, which are two states of magnetic particle, and it corresponds to 0 and 1.
- The reader of hard drive can realize the direction of each magnetic particle to convert it into 0 or 1 signals.
- The data to be stored on hard drive is a line of 0 or 1 signals. The recorder of hard drive relies on this signal and changes the direction of each magnetic particle accordingly. This is the principle of data storage of hard drive.
2- Byte
Byte is an unit in computer which is equivalent to 8 bits. Thus, a byte can represent a number in range of0 to 255.
How Many Bytes In Bit
Why is 1 byte equal to 8 bit?
Your question is now 'Why is 1 byte equal to 8 bits but not 10 bits?'.
At the beginning of computer age people have used baudot as a basic unit, which is equivalent to 5 bits, i.e. it can represent numbers from 0 to 31. If each number represents a character, 32 is enough to use for the uppercase letters such as A, B, ... Z, and a few more characters. It is not enough for all lowercase characters.
Immediately after, some computers use 6 bits to represent characters and can represent at maximum 64 characters. They are enough to use for A, B, .. Z, a, b.. Z, 0, 1, 2, .. 9 but not enough for other characters such as +,-,*, / and spaces.Thus, 6 bits quickly become to be restricted.
ASCII defined a 7-bit character set. That was 'good enough' for a lot of uses for a long time, and has formed the basis of most newer character sets as well (ISO 646, ISO 8859, Unicode, ISO 10646, etc.)
8-bit, a little bit more than 7-bit which is better. It doesn't cause too large waste. The 8-bit is a collection of numbers between 0 and 255 and it satisfies computer designers. The concept of byte was born, 1 byte = 8 bits.
For 8-bit, Designers can define other characters, including special characters in computer. ANSI code table was born which is inheritance of the ASCII code table:
There are many character sets with a view to encoding characters in different languages. For example, Chinese, Japanese require a lot of characters, in which case people uses 2 bytes or 4 bytes to define a character.
Table Of Content
1- Overview of data types
Any programming language has a set of data types. Data types are basic, and quite similar for all languages. All data types are composed from bits, therefore, I dedicate a post to introduce the history of bits and bytes. My advice is that you should read it before continuing reading this post.
Java has two types of data types:- Primitive Types
- Reference Types
There are 8 primitive data types which are boolean, byte, char, short, int, long, float, double.
| Data type | Default Value | Size |
|---|---|---|
| boolean | false | 1 bit |
| char | 'u0000' | 2 byte |
| byte | 0 | 1 byte |
| short | 0 | 2 byte |
| int | 0 | 4 byte |
| long | 0L | 8 byte |
| float | 0.0f | 4 byte |
| double | 0.0d | 8 byte |
- Logic type: boolean.
- Integer types: byte, short, char, int, long.
- Real number type is also called floating point: float, double.
Reference types, which are objects created by the constructor of classes.
2- byte
1 byte a byte is composed of 8 consecutive bits in the memory of computer. Each bit is a binary number of 0 or 1. Java uses 'byte' to name a integer type with small scope (Size: 1 byte).
The first bit in a row of 8 bits has value of 0 or 1.- If it is 0, Java considers it as + (Represent a positive number)
- If it is 1 Java considers it as - (Represent a negative number)
But wait, it is supposed to be [-128, 127], why?
Why is the smallest number of byte type in Java -128?
If the rules that the first bit has a value of 0 equivalent to +, the value of 1 equivalent to -, then we have two ways to represent 0 (see the illustration).
Therefore, the binary sequence of '1 0 0 0 0 0 0' should be considered as the smallest number of byte data type in Java. It represents -128.
3- boolean
boolean is the simplest data type. It has size of 1 bit. It has 2 values of true and false.
4- char
Eight Bit Byte Mac Os X
Although 'char' is the first four characters of the 'Character' term, the char type in Java is used to store non-negative integers with the two-byte size. It is also used to represent for a Unicode character because in nature, each character corresponds to a specific number. (This number is understood as the code of character.)
Because char is non-negative integer type, size: 2 bytes, its scope is [0, 2*16-1] ( [0, 65535] ).
When char is understood as a Unicode character, the smallest character is 'u0000' (Mã 0), and the largest character is 'uffff' (code: 65535).
- TODO
5- short
short is data type for the purpose of representing a two-byte integer (16 bits), including negative integer.
- The smallest value is -32,768 (-2^15) and the largest value is 32,767 (2^15 -1).
- Default value is 0.
** Note: See the explanation of the rule to determine the positive or negative number in the section of byte data type.
6- int
int data type is used to represent an integer with the size of 4 bytes (32 bits).
- The smallest value: -2,147,483,648 (-2^31)
- The largest value: 2,147,483,647 (2^31 -1)
- Default value: 0.
In Java, the int data type is considered as default data type for integers. Therefore, if you write 100, Java will create a four- byte memory area for storage. And if you want Java to create an eight- byte memory area to store 100, you have to write 100L. (long is an eight-byte integer type, introduced in the following section).
7- long
The long data type is used to represent integers with the size of 8 bytes (64 bits).
- The smallest value is -9,223,372,036,854,775,808.(-2^63)
- The largest value is 9,223,372,036,854,775,807. (2^63 -1)
- This type is used when a value pattern wider than int is necessary.
- Default value is 0L.
8- float
float data type is used to represent a real number with the size of 4 bytes (32 bits).
- The smallest value: -3.4028235 x 10^38
- The largest value:: 3.4028235 x 10^38
- Default value: 0.0f
9- double
double data type is used to represent a real number with the size of 8 bytes (64 bits). It is the default type for real numbers.
- The smallest value: -1.7976931348623157 x 10^308
- The largest value: 1.7976931348623157 x 10^308
- Default value: 0.0d
10- Reference Types
In Java, a data type created by a combination of primitive types is called a reference type. The most commonly used reference type is the String, which is a combination of characters.
Reference types are created based on a class. The class is like a blueprint to define a reference type.