整数的最大值 [英] max value of integer

问题描述

在 C 中，整数(对于 32 位机器)是 32 位，范围从 -32,768 到 +32,767.在 Java 中，整数(long)也是 32 位，但范围从 -2,147,483,648 到 +2,147,483,647.

In C, the integer (for 32 bit machine) is 32 bits, and it ranges from -32,768 to +32,767. In Java, the integer(long) is also 32 bits, but ranges from -2,147,483,648 to +2,147,483,647.

我不明白 Java 中的范围有何不同，即使位数相同.有人能解释一下吗?

I do not understand how the range is different in Java, even though the number of bits is the same. Can someone explain this?

推荐答案

在 C 中， 语言本身并不决定某些数据类型的表示.它可能因机器而异，在嵌入式系统上，int 可以是 16 位宽，但通常是 32 位.

In C, the language itself does not determine the representation of certain datatypes. It can vary from machine to machine, on embedded systems the int can be 16 bit wide, though usually it is 32 bit.

唯一的要求是 short int <= int <= long int 按大小.此外，还建议 int 应代表处理器的本机容量.

The only requirement is that short int <= int <= long int by size. Also, there is a recommendation that int should represent the native capacity of the processor.

所有类型都有签名.unsigned 修饰符允许您使用最高位作为值的一部分(否则它是为符号位保留的).

All types are signed. The unsigned modifier allows you to use the highest bit as part of the value (otherwise it is reserved for the sign bit).

以下是可能的数据类型的可能值的简短表格:

Here's a short table of the possible values for the possible data types:

          width                     minimum                         maximum
signed    8 bit                        -128                            +127
signed   16 bit                     -32 768                         +32 767
signed   32 bit              -2 147 483 648                  [phone]
signed   64 bit  -9 223 372 036 854 775 808      [phone] 775 807
unsigned  8 bit                           0                            +255
unsigned 16 bit                           0                         +65 535
unsigned 32 bit                           0                  [phone]
unsigned 64 bit                           0     [phone] 551 615

在 Java 中，Java 语言规范决定了数据类型的表示.

In Java, the Java Language Specification determines the representation of the data types.

顺序为:byte 8 bits, short 16 bits, int 32 bits, long 64 bits.所有这些类型都是签名，没有未签名的版本.但是，位操作将数字视为无符号数(即正确处理所有位).

The order is: byte 8 bits, short 16 bits, int 32 bits, long 64 bits. All of these types are signed, there are no unsigned versions. However, bit manipulations treat the numbers as they were unsigned (that is, handling all bits correctly).

字符数据类型 char 为 16 位宽，无符号，并使用 UTF-16 编码保存字符(但是，可以分配一个 char 一个任意的无符号 16 位整数，表示一个无效的字符代码点)

The character data type char is 16 bits wide, unsigned, and holds characters using UTF-16 encoding (however, it is possible to assign a char an arbitrary unsigned 16 bit integer that represents an invalid character codepoint)

          width                     minimum                         maximum

SIGNED
byte:     8 bit                        -128                            +127
short:   16 bit                     -32 768                         +32 767
int:     32 bit              -2 147 483 648                  [phone]
long:    64 bit  -9 223 372 036 854 775 808      [phone] 775 807

UNSIGNED
char     16 bit                           0                         +65 535

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