unsigned | 易学教程

Why doesn't Java support unsigned ints?

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问题 Why doesn\'t Java include support for unsigned integers? It seems to me to be an odd omission, given that they allow one to write code that is less likely to produce overflows on unexpectedly large input. Furthermore, using unsigned integers can be a form of self-documentation, since they indicate that the value which the unsigned int was intended to hold is never supposed to be negative. Lastly, in some cases, unsigned integers can be more efficient for certain operations, such as division.

Can we make unsigned byte in Java

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问题 I am trying to convert a signed byte in unsigned. The problem is the data I am receiving is unsigned and Java does not support unsigned byte, so when it reads the data it treats it as signed. I tried it to convert it by the following solution I got from Stack Overflow. public static int unsignedToBytes(byte a) { int b = a & 0xFF; return b; } But when again it\'s converted in byte, I get the same signed data. I am trying to use this data as a parameter to a function of Java that accepts only a

Is unsigned integer subtraction defined behavior?

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I have come across code from someone who appears to believe there is a problem subtracting an unsigned integer from another integer of the same type when the result would be negative. So that code like this would be incorrect even if it happens to work on most architectures. unsigned int To, Tf; To = getcounter(); while (1) { Tf = getcounter(); if ((Tf-To) >= TIME_LIMIT) { break; } } This is the only vaguely relevant quote from the C standard I could find. A computation involving unsigned operands can never overﬂow, because a result that cannot be represented by the resulting unsigned integer

How to determine a Python variable's type?

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问题 How do I see the type of a variable whether it is unsigned 32 bit, signed 16 bit, etc.? How do I view it? 回答1: Python doesn't have the same types as C/C++, which appears to be your question. Try this: >>> i = 123 >>> type(i) <type 'int'> >>> type(i) is int True >>> i = 123456789L >>> type(i) <type 'long'> >>> type(i) is long True >>> i = 123.456 >>> type(i) <type 'float'> >>> type(i) is float True The distinction between int and long goes away in Python 3.0, though. 回答2: You may be looking

Redis 数据结构与内存管理策略（下）

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Redis 数据结构与内存管理策略（下）标签： Redis Redis数据结构 Redis内存管理策略 Redis数据类型 Redis类型映射 Redis 数据类型特点与使用场景 String 、 List 、 Hash 、 Set 、 Zset 案例：沪江团购系统大促 hot-top 接口 cache 设计 Redis 内存数据结构与编码 OBJECT encoding key、 DEBUG OBJECT key 简单动态字符串（simple dynamic string）链表（linked list）字典（dict）跳表（skip list）整数集合（int set）压缩表（zip list） Redis Object 类型与映射 Redis 内存管理策略键过期时间、生存时间过期键删除策略 AOF 、 RDB 处理过期键策略 Redis LRU 算法 Redis 持久化方式 RDB (Redis DataBase) AOF (Append-only file) 字典（dict） dict 字典是基于 hash算法来实现，是 Hash 数据类型的底层存储数据结构。我们来看下 redis 3.0.0 版本的 dict.h 头文件定义。 typedef struct dict { dictType *type; void *privdata; dictht ht

Signed/unsigned comparisons

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问题 I\'m trying to understand why the following code doesn\'t issue a warning at the indicated place. //from limits.h #define UINT_MAX 0xffffffff /* maximum unsigned int value */ #define INT_MAX 2147483647 /* maximum (signed) int value */ /* = 0x7fffffff */ int a = INT_MAX; //_int64 a = INT_MAX; // makes all warnings go away unsigned int b = UINT_MAX; bool c = false; if(a < b) // warning C4018: \'<\' : signed/unsigned mismatch c = true; if(a > b) // warning C4018: \'<\' : signed/unsigned mismatch

What happens if I assign a negative value to an unsigned variable?

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问题 I was curious to know what would happen if I assign a negative value to an unsigned variable. The code will look somewhat like this. unsigned int nVal = 0; nVal = -5; It didn\'t give me any compiler error. When I ran the program the nVal was assigned a strange value! Could it be that some 2\'s complement value gets assigned to nVal ? 回答1: For the official answer - Section 4.7 conv.integral "If the destination type is unsigned, the resulting value is the least unsigned integer congruent to the

Comparison operation on unsigned and signed integers

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问题 See this code snippet int main() { unsigned int a = 1000; int b = -1; if (a>b) printf(\"A is BIG! %d\\n\", a-b); else printf(\"a is SMALL! %d\\n\", a-b); return 0; } This gives the output: a is SMALL: 1001 I don\'t understand what\'s happening here. How does the > operator work here? Why is \"a\" smaller than \"b\"? If it is indeed smaller, why do i get a positive number (1001) as the difference? 回答1: Binary operations between different integral types are performed within a "common" type

时钟设置函数的过程梳理及编写

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stm32的HSI能够达到8MHZ，但是通过软件的设置，能够让stm32工作在72MHZ。接下来，就来完整的写一遍时钟设置函数。 stm32通过操纵寄存器到达编程控制硬件的目的。因此，首先要开一个.h的头文件做一些基本的设置。 #ifndef __CLOCK_H__ #define __CLOCK_H__ 接下来，在这其中做一些寄存器的宏定义： #define RCC_BASE 0x40021000 #define RCC_CR ( RCC_BASE + 0x00 ) #define RCC_CFGR ( RCC_BASE + 0x04 ) 当然，如果想要使用寄存器，那么就要对寄存器进行指针解引 #define rRCC_CR *( ( unsigned int * ) RCC_CR ) #define rRCC_CFGR *( ( unsigned int * ) RCC_CFGR ) #endif 以上，基本上，就已经把所需要的寄存器配置好了。然后，新建一个.c文件，开始写时钟设置函数，那么将这个时钟设置函数命名为：void Set_SysClockTo72M(void); 在这个函数中，首先，进行一个基本的变量定义： unsigned int rccCrHserdy = 0; unsigned int rccCrPllrdy = 0; unsigned int