precalculus chapter 3

Monkeysourcenetwork, or subclasses of Monkeysourcenetworkvars, Otherwise it is Monkeysourcenetworkviews's subclass:Figure 6-3-2 Command translation class as the inner class of the event sourceOnce the event source gets to the string command it is convenient to call the internal command translation class through Command_map to translate the command, so we can also think that the event source relies on the corresponding command translation class to do

Monkeysourcenetwork, or subclasses of Monkeysourcenetworkvars, Otherwise it is Monkeysourcenetworkviews's subclass:Figure 6-3-2 Command translation class as the inner class of the event sourceOnce the event source gets to the string command it is convenient to call the internal command translation class through Command_map to translate the command, so we can also think that the event source relies on the corresponding command translation class to do

color does not exist ("red" is returned), it will be processed. However, if the product does not exist, it will not be processed. That is to say, the product must exist. Otherwise, the template will report an error. (product.color)!"red" If the product does not exist or the product does not exist and the color does not exist, the default value "red" is displayed without an error. The default operation can also act on the sequence, for example: Output: ab\-\-3.3.13.2 check for nonexistent value

Chapter 3 process description and Control 1. What is a process? A program being executed Program instance being executed on Computer Entity that can be allocated to the processor and executed by the processor An activity unit with the following features: execution of a set of command sequences, a set of current states and related system resources Processes can be characterized as the following elements: I

a command, not "VI sudo", can also #vim/etc/sudoers file )root all= (All) all// authorizing the root useris the address of the managed host #用户名 (can use Identity) Authorization command (absolute path), respectively. where "user name" indicates which user is authorized , " address of Managed host " indicates which host the user can run authorization command on (all means any host), " can use identity " indicates the identity of the test user to run the authorization command , which is omitted.

Chapter 3 of basic PHP syntax-process control. I. Condition Statement 1. if statement syntax: if (condition statement 1) for example $ a $ B or $ a $ B {command executed when Condition Statement 1 is met, for example, echoa is greater than B ;} elseif (condition statement 2) for example $ a 1. Condition Statement 1. if statement syntax: If (condition 1) for example $ a = $ B or $ a> $ B { Command e

represents the data type generated at initialization, and if it is int, it is an int type node;Its values members record the parameters of the function, which is a struct TREE_INT_CST type, which concatenates several parameters through its chain;For such a source code:void Main (){}It eventually turns into a syntax tree, but the tree has only one node, which is the node that represents the function, which is actually a struct TREE_DECL structure whose name member representsThe name of the funct

Deep understanding of Java Virtual Machine-Chapter 3: deep understanding of Java Virtual Machine 1. Overview 2. Is the object dead? Reference Counter Add a reference counter to the object. When there is a reference, add 1 to the counter. When the reference is invalid, the counter minus 1. Objects whose counter is 0 at any time cannot be used again. If the object is a circular reference, it cannot be process

deleted, the remaining element index value is automatically minus 1) Pop and shift return the deleted element EG: array. Pop (); Array. Shift (); (4) Splice: You can insert or delete elements in an array flexibly. (5) Slice: Gets the partial element in the array. Note: The difference between splice and slice. (6) Concat: Combining multiple elements or arrays into a new array Note: The difference between concat and push. 3. Deep copy

not allow null values, there is no default clause, which affects MySQL's handling of columns:1.如果没有启用SQL的严格模式，这列将会被设置成其数据类型的隐含默认值。2.启用SQL严格模式之后，如果表是事务性的，就会出现错误。这条语句会中止执行，然后回滚。对于非事务性的表，如果这行是该语句插入的第一个行，那么会出现一个错误，该语句中止执行，如果不是第一行，那么可以选择中止执行，或选择把这列设置为它的隐含默认值，同时发出一条警告信息The implied default value of a column depends on its data type.1.对于数字列（不包含那些具有auto_increment属性的列），其默认值为0. 对于auto_increment列，默认值是下一个列的列序号。2.对于大多数时态类型列，其默认值为该类型的“零”值 对于enum列，默认值为枚举集里的第一个元素， 对于set列，如果不允许NULL值，默认值将是一个空集不过它等价于空串。

Chapter 3 CopyOnWriteArrayList source code parsing: copyonwritearraylist Note: Before reading this article, if you are not clear about the underlying layer of ArrayList, we recommend that you check it first.ArrayListSource code parsing. Http://www.cnblogs.com/java-zhao/p/5102342.html 1. Master the following points for CopyOnWriteArrayList: Create: CopyOnWriteArrayList () Add element: add (E) Method Get

to shuffle, you have n cards, first throw away, and then put the first one in the end, and then the first card to throw away, the remaining one card and then output you throw away this card. Would have thought of using an array analogy, similar to Joseph Ring. But GG, I tried a few groups did not, and then they were hanging in that, changed a long array suddenly found a lot of people ac, I think maybe the array is more troublesome, I need to shake clever think of some other data structure, a be

will enter the editing interface of the diary:Figure 2-3-2 Editing Note2 's Noteeditor interfaceThe Activity window consists of two controls, the first is the title, is a TextView control, the second is the journal content, is an editable edittext control, we can modify the content inside. After entering the interface, the soft keyboard will automatically pop out for user input.Let's take a look at the property content of the two controls in Uiautoma

: string s1;string s2(s1);string s3("abcd");string s4(n,‘c‘); 3: Operation s.empty(); s.size() s[n]; s1==s2; s1=s2 s1!=s2; s1>s2;//>= s1 4: Type: String: size_type and unsigned machine type; 5: The character must have the operator + and a character type variable between the left and right. 6: About the character handler function in the header file cctype. 7: Type: vector Second: vector type 1: The vector is not a data type, but a class template. 2: C

the first person to call, each time we have to determine whether we reach the last person, with the counter-clockwise we have to judge each time whether to reach the first end of the team.Then do the output.There are still deficiencies in this exercise:For the vim of the sub-screen operation is not proficient, to be strengthened, for debugging s,n in the end it is time to execute an instruction or a number of instructions are unclear. Low commissioning efficiency.Experience:For a number of oper

iuse%mounted on3/dev/sda28855552 219633 8635919 3% /4None1532516 2 1532514 1%/sys/fs/Cgroup5Udev1529802 463 1529339 1% /Dev6Tmpfs1532516 523 1531993 1% /Run7None1532516 A 1532504 1%/run/Lock8None1532516 1 1532515 1%/run/SHM9None1532516 3 1532513 1%/run/UserTen/dev/sda10 0 0-/boot/efiYou can see that the I nodes of the current file system are suffici

ROW--when a record is modified to the employee tableINSERT into Test_log (content) VALUES (' employee table modified a record ');-- ModificationUPDATE employee SET empname= ' Eric ' WHERE id=7;-- CREATE Trigger ( Delete )CREATE TRIGGER Tri_empdel After delete on employee for each ROW--when a record is deleted to the employee tableINSERT into Test_log (content) VALUES (' employee table Delete a record ');-- DeleteDELETE from employee WHERE id=7; 7 MySQL permissions issues -

Computing square (2 )... 4 Computing square (3 )... 9 ---- Collection updated --- Computing square (11 )... 121 Computing square (12 )... 144 Computing square (13 )... 169 The query is executed again in the second iteration and new results are obtained. The query is executed immediately. We can see that delayed execution is the default query behavior. That is, the query starts only when data is requested. If we want the query to be executed immediate

Chapter 3 the core idea of cache search engine caching Cache Optimization is to improve the throughput of the queryer by avoiding unnecessary and repetitive CPU computing and I/O scheduling. The traditional cache has two levels: first, the cache of the result set records the query keywords and returned results. If the same keywords are accessed again, the system will respond quickly and filter the calculati

spark cluster; Spark_worker_memoery: The maximum memory size that can be allocated to the specified worker node to the excutors. Because the three servers are configured with 2 GB memory, this parameter is set to 2 GB for the sake of full memory usage; Hadoop_conf_dir: Specifies the directory of the configuration file of our original hadoop cluster; Save and exit. Next, configure the slaves file under SPARK conf and add all worker nodes to it: Content of the opened file: We need to modify th