What are the data types?

Data types include: 1. Integer type [byte, short, int, long]; 2. Floating point type [float, double]; 3. Character type char; 4. Boolean type boolean.

The operating environment of this article: Windows10 Home Chinese version, Acer S40-51 computer.

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The data types are:

1) Four integer types ( byte, short, int, long):

• byte: 8 bits, used to represent the smallest data unit, such as data in a file, -128~127

• short: 16 bits, rarely used, -32768 ~ 32767

• int: 32 bits, most commonly used, -2^31-1~2^31 (2.1 billion)

• long: 64 bits, commonly used

Notes: int i=5; // 5 is called a direct quantity ( or literal), that is, a constant written directly.

Integer literals are of type int by default, so add L or l after the defined long data.​

Variables less than 32 digits are calculated as int results.​

Forced operators have higher priority than mathematical operators. See Constants and Variables for examples.

2) Two types of floating point numbers (float, double):

float: 32 bits, suffix F or f, 1 sign bit, 8-bit exponent, 23 valid mantissas.

double: 64 bits, most commonly used, suffix D or d, 1 sign bit, 11 bits of exponent, 52 bits of effective tail

Notes:

Binary floating point number : 1010100010=101010001.0*2=10101000.10*2^10 (2nd power)=1010100.010*2^11 (3rd power)= . 1010100010*2^1010 (10th power)

Mantissa: . 101010001 0

Exponent: 1010

Base: 2

Floating point numeric values ​​are of double type by default, so add F or f after the defined float type data; double type is not required Write the suffix, but be sure to write D or X. The range of

float is larger than long and the exponent can be very large.​

Floating point numbers are inexact, and floating point numbers cannot be accurately compared.

3) A character type (char):

char: 16 bits, an integer type, 1 character enclosed in single quotes (can be a Chinese characters), using Unicode code to represent characters, 0~2^16-1 (65535).​

Note: Cannot be 0 characters.

Escape characters: \n Line feed \r Carriage return \t Tab character \" Double quotation mark \\ represents a \

Two characters char are connected with " " in the middle, and the characters are converted internally first into int type, and then perform addition operation, char is essentially a number! Binary, when displayed, it is "processed" and displayed as characters.

4) A Boolean type (boolean): true True and false.

5) Type conversion:

char--> Automatic conversion: byte-->short-->int -->long-->float-->double                                                                                                                                                                                                                                          through

8 bits: Byte (byte type) 16 bits: short (short integer type), char (character type)

32-bit: int (integer), float (single-precision/floating-point)

64-bit: long (long integer), double (double-precision)

Last one: boolean Boolean type

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