大约有 23,000 项符合查询结果（耗时：0.0221秒） [XML]
How to make MySQL handle UTF-8 properly
... worry utf8mb4 taking extra storage when most text is ASCII. Although char strings are preallocated, varchar strings are not -- see the last few lines on this documentation page. For example, char(10) will be pessimistically reserve 40 bytes under utf8mb4, but varchar(10) will allocate bytes in kee...
#pragma pack effect
...ing a DWORD at an address which isn't divisible by 4 requires at least one extra CPU cycle on a 32 bit processor. So, if you have e.g. three char members char a, b, c;, they actually tend to take 6 or 12 bytes of storage.
#pragma allows you to override this to achieve more efficient space usage, a...
Lost connection to MySQL server at 'reading initial communication packet', system error: 0
...ggests that it might be because the MySQL server is bound to the loop-back IP (127.0.0.1 / localhost) which effectively cuts you off from connecting from "outside".
If this is the case, you need to upload the script to the webserver (which is probably also running the MySQL server) and keep your se...
Using ping in c#
...
using System.Net.NetworkInformation;
public static bool PingHost(string nameOrAddress)
{
bool pingable = false;
Ping pinger = null;
try
{
pinger = new Ping();
PingReply reply = pinger.Send(nameOrAddress);
pingable = reply.Status == IPStatus.Success;...
java.net.UnknownHostException: Invalid hostname for server: local
...ther. Everything was right.
The Solution
Not calling trim() for the host string which contained whitespace. In writing a proxy server the host was obtained from HTTP headers with the use of split(":") by semicolons for the HOST header. This left whitespace, and causes the UnknownHostException as a...
Is gcc's __attribute__((packed)) / #pragma pack unsafe?
...7
p1 = ffbff31c
Bus error
In both cases, the program is compiled with no extra options, just gcc packed.c -o packed.
(A program that uses a single struct rather than array doesn't reliably exhibit the problem, since the compiler can allocate the struct on an odd address so the x member is properl...
How Can I Download a File from EC2 [closed]
...
Use scp:
scp -i ec2key.pem username@ec2ip:/path/to/file .
where:
ec2key.pem is your PEM key
username is the username you log in with
ec2ip is the IP or DNS alias of the instance
/path/to/file is the location where the file is stored
This will copy the file i...
Why use bzero over memset?
...lient/server in C. When initializing the structs, like sock_addr_in , or char buffers (that we used to send data back and forth between client and server) the professor instructed us to only use bzero and not memset to initialize them. He never explained why, and I'm curious if there is a val...
VC IP地址控件（CIPAddressCtrl ）的自绘 - C/C++ - 清泛网 - 专注C/C++及内核技术
VC IP地址控件（CIPAddressCtrl ）的自绘先看效果图：代码：.h#pragma once class CMyIPCtrl : public CIPAddressCtrl{DECLARE_DYNAMIC(CMyIPCtrl)public:CMyIPCtrl();virtua...先看效果图：
代码：
.h
#pragma once
class CMyIPCtrl : public CIPAddressCtrl
{
DECLARE_DYNAMI...
Regexp Java for password validation
...[@#$%^&+=])(?=\S+$).{8,}$
Explanation:
^ # start-of-string
(?=.*[0-9]) # a digit must occur at least once
(?=.*[a-z]) # a lower case letter must occur at least once
(?=.*[A-Z]) # an upper case letter must occur at least once
(?=.*[@#$%^&+=]) # a special ...