unsigned | 易学教程

虹软人脸识别SDK在网络摄像头中的实际应用

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目前在人脸识别领域中，网络摄像头的使用很普遍，但接入网络摄像头和人脸识别SDK有一定门槛，在此文章中有介绍过虹软人脸识别SDK的接入流程，本文着重介绍网络摄像头获取视频流并处理的流程(红色框内)，以下内容仅供参考。 1.海康SDK接入基本流程 a.初始化并登录验证 NET_DVR_Init(); NET_DVR_DEVICEINFO_V30 struDeviceInfo = { 0 }; long lUserID = NET_DVR_Login_V30(m_cameraIp, m_cameraPort, m_cameraUser, m_cameraPwd, &struDeviceInfo); if (lUserID < 0) { NET_DVR_Cleanup(); return false; } b.创建线程并注册回调函数 thread videoThread(&HCNetCamera::getCameraPreview, this); videoThread.detach(); bool HCNetCamera::getCameraPreview() { NET_DVR_CLIENTINFO ClientInfo; ClientInfo.lChannel = 1; //Channel number 设备通道号 ClientInfo.hPlayWnd = NULL; //窗口为空

Are there languages compatible with .NET that don't support unsigned types?

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问题 Let's say that I'm writing a library in C# and I don't know who is going to consume it. The public interface of the library has some unsigned types - uint, ushort. Apparently those types are not CLS-compliant and, theoretically speaking, there may be languages that will not be able to consume them. Are there in reality languages like that? 回答1: I believe in the original version of VB.NET, unsigned types were usable but there was no support for them built into the language. This has been

Unsigned versus signed numbers as indexes

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问题 Whats the rationale for using signed numbers as indexes in .Net? In Python, you can index from the end of an array by sending negative numbers, but this is not the case in .Net. It's not easy for .Net to add such a feature later as it could break other code perhaps using special rules (yeah, a bad idea, but I guess it happens) on indexing. Not that I have ever have needed to index arrays over 2,147,483,647 in size, but I really cannot understand why they choose signed numbers. Can it be

Unsigned versus signed numbers as indexes

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Using ruby to convert unsigned integers stored as signed back to the original value

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问题 A C-program is placing what it considers to be 64-bit unsigned integers into a column in a Postgres database that is typed as int8. To Postgres, int8 is always 'signed int8' (no such thing to it as 'unsigned int8'). So the Ruby program I have shows numbers retrieved from Postgres in the upper half of that space as negative. What is the correct way, in Ruby, to take that -ve integer and convert it to the 64-bit unsigned integer that the C-programmer intended? 回答1: I'm not sure of Ruby

Casting an array of unsigned chars to an array of floats

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问题 What is the best way of converting a unsigned char array to a float array in c++? I presently have a for loop as follows for (i=0 ;i< len; i++) float_buff[i]= (float) char_buff[i]; I also need to reverse the procedure, i.e convert from unsigned char to float (float to 8bit conversion) for (i=0 ;i< len; i++) char_buff[i]= (unsigned char) float_buff[i]; Any advice would be appreciated Thanks 回答1: I think the best way is to use a function object: template <typename T> // T models Any struct

How does adding MIN_VALUE compare integers as unsigned?

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问题 In Java the int type is signed, but it has a method that compares two ints as if they were unsigned: public static int compareUnsigned(int x, int y) { return compare(x + MIN_VALUE, y + MIN_VALUE); } It adds Integer.MIN_VALUE to each argument, then calls the normal signed comparison method, which is: public static int compare(int x, int y) { return (x < y) ? -1 : ((x == y) ? 0 : 1); } How does adding MIN_VALUE to each argument magically make the comparison unsigned? 回答1: This technique works

Gcc: force compiler to use unsigned char by default

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问题 Since the nature of a char in C++ is compiler-dependent when the unsigned qualifier is not present, is there an argument I could pass on to GCC which would force all char s to be compiled as unsigned ? 回答1: The flag you are looking for is -funsigned-char . From the documentation: -funsigned-char Let the type char be unsigned, like unsigned char . Each kind of machine has a default for what char should be. It is either like unsigned char by default or like signed char by default. Ideally, a

Java SHA-1 hash an unsigned BYTE

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问题 Hy guys! I have the following problem: I need to hash an unsigned byte in Java which is(would be...) between 0-255. The main problem is that java doesnt have an unsigned Byte type at all. I found a workaround for this, and used int instead of byte with a little modification. The main problem is: Java.securitys Messagedigest.digest function only accepts byte array types, but i would need to give it an int array. Anybody has a simpe workaround for this? I was looking for a third party sha-1

C语言随机函数

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 在C语言中,rand()函数可以用来产生随机数，但是这不是真真意义上的随机数，是一个伪随机数，是根据一个数，我们可以称它为种子，为基准以某个递推公式推算出来的一系数，当这系列数很大的时候，就符合正态公布，从而相当于产生了随机数，但这不是真正的随机数，当计算机正常开机后，这个种子的值是定了的，除非你破坏了系统，为了改变这个种子的值，C提供了srand()函数，它的原形是void srand( int a)。可能大家都知道C语言中的随机函数random，可是random函数并不是ANSI C标准，所以说，random函数不能在gcc,vc等编译器下编译通过。 rand()会返回一随机数值，范围在0至RAND_MAX 间。返回0至RAND_MAX之间的随机数值，RAND_MAX定义在stdlib.h，(其值至少为32767)我运算的结果是一个不定的数，要看你定义的变量类型，int整形的话就是32767。在调用此函数产生随机数前，必须先利用srand()设好随机数种子，如果未设随机数种子，rand()在调用时会自动设随机数种子为1。一般用for语句来设置种子的个数。具体见下面的例子。一、如何产生不可预见的随机序列呢利用srand((unsigned int)(time(NULL))是一种方法