computer drawing programs

Thinking logic of computer programs (64) and thinking 64 For file processing, we introduced the stream method, section 57 introduced the byte stream, section 58 introduced the ghost stream, and also introduced the underlying file operation method, section 60 describes random read/write files, Section 61 Describes memory ing files, Object serialization/deserialization mechanisms, and section 62 describes Jav

Thinking logic of computer programs (14), thinking Logic It is said that Tao shengyi has a second, second, and third life. If binary representation and operation are regarded as one, the basic data type is regarded as two, and the basic data type is regarded as three, then, the combination of classes and the inheritance introduced in the next section make the three born things. In the previous section, we i

Thinking logic of computer programs (73) and thinking 73 In this section and the following sections, we will discuss the container classes in Java and package. This section describes two simple classes, CopyOnWriteArrayList and CopyOnWriteArraySet, and discusses their usage and implementation principles. Their usage is relatively simple. What we need to understand is their implementation mechanism: Copy-On-

Thinking logic of computer programs (13), thinking Logic Class In the previous section, we introduced the basic principles of function calling. In this section and the next sections, we will explore the world of classes. Programs mainly involve data and operations on data. To facilitate understanding and operation, advanced languages use the data type concept. Di

control the memory, hard disk, and the like. These commands cannot be directly executed by the program to prevent malicious programs from damaging the system, this is a kind of protection for the CPU, and the loop 3 command can be directly called by anyone, and can be used as a user interface. Programming: Computer languages include interpreted and compiled languages. Interpreted language: the source code

Thinking logic of computer programs (87) and thinking 87 In the previous section, we discussed dynamic proxies. in the previous sections, we mentioned ClassLoader for many times. This section will discuss in detail the class loading mechanism and ClassLoader in Java. ClassLoader is the Class for loading other classes. It is responsible for loading bytecode files to the memory and creating Class objects. Lik

Unnecessary programs in Windows How to prohibit the operation, the computer after a period of time will appear some unnecessary procedures, will affect the speed of our computer, if you do not need to prohibit these programs to start on it. But how to forbid it? The following three networks tell you the specific steps.

Thinking logic of computer programs (51) and thinking 51 The previous section describes EnumMap. This section also describes the implementation class EnumSet for the Set interface of the enumeration type. Similar to EnumMap, there is a special implementation class for enumeration types, mainly because it can implement the Set interface very efficiently. The implementation class HashSet/TreeSet of the Set in

Many friends may think that after the Win7 32-bit system is turned on, only we open the program is the start of the program, in fact, you may wish to try to open the computer's Task Manager window, in the process of this column is not to see a lot of content, actually these are currently starting in the program, that is to say, Many programs are open when we open the computer, then in many

Thinking logic of computer programs (5), thinking Logic Intuitive fact violations The reason why a computer is called a "computing" machine is because it was invented mainly for computing. "computing" is of course its specialty. In everyone's impression, computing must be very accurate. But in fact, even in some basic decimal operations, the calculation results a

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

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