best architecture computer programs

corresponds to Java.In 32-bit format, 1 bits represent the symbol, 23 bits represent the mantissa, and 8 bits represent the exponent. In 64-bit format, 1 bits represent the symbol, 52 bits represent the mantissa, and 11 bits represent the exponent.In the two formats, in addition to the normal number, the standard also specifies that some special binary forms represent some special values, such as negative infinity, positive infinity, 0,nan (non-numeric, such as 0 times infinity).The IEEE 754 st

Thinking logic of computer programs (67) and thinking 67 The previous section introduced the problem of competing multiple threads to access the same resource and the solution synchronized. we mentioned that in addition to competition among multiple threads, mutual collaboration is often required, this section describes the basic mechanism of multi-thread collaboration in Java. What scenarios need collabora

stack frame was just destroyed. Later, if the program assigns a value to *p, it may actually be modifying the data in another function stack frame, potentially with disastrous and confusing consequences.9. Referencing data in a free heap blockA typical error is referencing data from a heap block that has been freed, for example:[CPP]View PlainCopy int * HEAPREF (int n, int m) { int i; int *x, *y; x = (int *) Malloc (n * sizeof (int)); / * Various operations * / Free (x);

conditional expression:Each p (condition) is evaluated in turn, and the value corresponding to the first condition that is not false is evaluated with its value as the entire cond expression.(cond ( 1>) ; (…( )Expressions such as PN (to find a true or false value) are called predicates.It can be written in scheme: (define (abs x) (cond (> x 0 ) x) ( (= x 0 ) 0 ) x 0 ) (- x) ) ) ) In addition to predicates such as >=(And ...) Evaluates e one at a-until an e is calculated,

At plans to run commands and Program . The at command can only be used when the "scheduler" service is running. If you use it without parameters, at lists the scheduled commands. SyntaxAt [\ computername] [{[ID] [/delete] |/Delete [/Yes]}] At [[\ computername] hours: minutes [/interactive] [{/every: Date [,...] |/next: Date [,...]}] command] Parameters\ ComputernameSpecify a remote computer. If this parameter is omitted, the at program plans c

to log on to another host on the network (a remote system) to become that host. After the login is successful, the local user can manipulate the resources of the network host as a user of the remote system.With Telnet, the local computer can get "contacted" and interact with another remote computer on the network 程序 .3.FTP服务：FTP is both a protocol for controlling file transfers and an application. As an ap

then sleeps for a while, then sets shutdown to true and finally outputs "exit main".The expected result is that all two threads exit, but actually executes, it is likely to be found that Hellothread never exits, that is, in the Hellothread execution flow, shutdown is always false, even if the main thread has changed to true.What's going on here? This is the memory visibility issue. In a computer system, in addition to memory, the data is also cached

Thinking logic of computer programs (49), thinking 49 Previously, we introduced two implementation classes HashMap and TreeMap of the Map interface. This section introduces another implementation class LinkedHashMap. It is a subclass of HashMap, but it can keep the elements sorted by insert or access, which is different from the TreeMap key sorting. It is easy to understand the order by insert. What does th

, we briefly introduce Linkedhashset, which is a subclass of HashSet, but uses linkedhashmap internally.If you need a map implementation class, and the type of the key is an enumeration type, you can use HashMap, but you should use a dedicated implementation class Enummap, why? Let's discuss it in the next section.----------------To be continued, check out the latest articles, please pay attention to the public number "old Horse Programming" (Scan the QR code below), from the introduction to adv

expression is not used. (Execution efficiency is not necessarily high compared to other algorithms, and is only used to verify that the program's processing power is enhanced through rules, and that the regular expressions and program logic are not rigorously written without deep validation due to no in-depth testing)In fact, although the program is very simple, but, in fact, is a simple rule of the prototype engine.First, he loads a lot of business processing rules, plus, minus, multiply, divi

rule of the prototype engine.First, he loads a lot of business processing rules, plus, minus, multiply, divide, interpolate, index, remainder and so on.Second, his business rules can be extended continuously.Thirdly, as long as the facts are given, finally, by the constant application of the rules, he will eventually export the result, either the correct result or the fact that it is wrong.For children who need the source code, please go to git and get the codes directly.Git address: http://git

The system has become extremely difficult recently.QQ landing on the card, NetEase cloud music into not go, cool dog card dead, iOS simulator card dead ...All kinds of perverted cards dieCheck all over the network, call customer service, clear cache, re-install the system still no solution?????Half a month, it's torture.When I was about to give up my Mac, I looked at Performance Monitor and found that the programs that were stuck were all needed for a

Thinking logic of computer programs (79), thinking 79 In the previous section, we mentioned that in asynchronous task programs, a common scenario is that the main thread submits multiple asynchronous tasks and then processes the results if a task is completed, in this scenario, Java provides a convenient method for sending and distributing packets. The Completion

Thinking logic of computer programs (30), thinking Logic The previous section introduced the String, and mentioned that if String modification operations are frequent, StringBuilder and StringBuffer classes should be used. The methods of these two classes are basically the same, and their implementation code is almost the same, the only difference is that StringBuffer is thread-safe, while StringBuilder is

The MySQL service on the local computer is stopped after it is started. Some services will be automated when they are not used by other services or programs, and other mysql services Re-install the MySQL database. Due to the sloppy installation, all the way to next (in fact, strict configuration is required in some places and I forgot to pay attention to it), it is a lot of trouble now. Error message: Th

We often encounter open application prompts "Do you want to allow the following programs to make changes to this computer?" "If we do not like this much, then how to close the tip of the tube, specifically as follows." 1. Right-click the Start menu, as follows.2. Click on the "Control Panel" option to enter the Control Panel management.3. Click on the "User account and Home security" option, as shown below

Thinking logic of computer programs (59) and thinking 59 The previous two sections show you how to read and write file content through a stream. This section describes operations on file metadata and directories. File and directory operations are ultimately related to the operating system and file system. The implementations of different systems are different, but Java. io. the File class provides a unified

Thinking logic of computer programs (80) and thinking 80 This section describes scheduled tasks. There are many application scenarios for scheduled tasks, such: An alarm program or task reminder. You can call a bed at a specified time or return a credit card on a specified date. The monitoring system collects system data at intervals to trigger alarms for abnormal events. Statistical System, which usual

Thinking logic of computer programs (78) and thinking 78 In the previous section, we initially discussed the task execution service in Java and package. In reality, the main implementation mechanism of the task execution service is the thread pool. In this section, we will discuss the thread pool. Basic Concepts A thread pool, as its name implies, is a thread pool. There are several threads in it. They are

Thinking logic of computer programs (74) and thinking 74 This section describes a commonly used concurrent container-ConcurrentHashMap, which is a concurrent version of HashMap. Compared with HashMap, it has the following features: Concurrency Security Directly supports atomic composite operations Supports high concurrency, fully parallel read operations, and parallel write operations to a certain exten