After the storm from blog to mailing list, roadmap of New groovy appeared. To some extent, this is a response to groovy is dead, which has been so popular recently. On the other hand, Mike spille, groovy's neighborhood, responded to the criticism of the New groovy feature in the form of a wiki document.
This is the most controversial of all new features, of course: return/break/continue to behave inside closures like these statements work in other bl
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-A, -- all
Do not ignore entries starting.
2. touch, cat, and less commands
The touch command can create any type of files with a size of 0 in Linux. As a program developer, you can use the touch command to create files on a Linux Server:
Syntax: touch
Touch demo.txt
Root @ devopscube :~ # Touch demo.txt
Root @ devopscube :~ # Ls
Demo.txt
The cat command is used to view the content of a file, but the cat command cannot edit the content of the file. It can only browse the content of the file.
you omit Filehandle, STDOUT will also be regarded as a fixed Filehandle. before introducing the printf function, let's take a look at the characters that transform symbols in the printf function.
Symbol% C characters% S string% D integer% F floating integer% H hexadecimal code% O octal codeExample: Printf ("chomod % d % s \ n", "711" "cgi"); the chmod 711 cgi is added with a line break and displayed on the screen.
Command: Chop Syntax: chop ($ url)Description: Delete the last character.Example
The block in Ruby is generally translated into blocks of code, which seems a bit strange at first because there is no such thing in many languages. Actually, it's not bad.first-class function and Higher-order function
The first-class function and the Higher-order function are concepts in functional programming languages that sound like high-end, but very simple.
First-class functions refers to that in some languages, functions are first-class citizens, and functions can be passed as arguments.
the data file does not have any definite order. If we create an index of the name column, MySQL sorts the name column in the index, and for each item in the index, MySQL internally saves it a "pointer" to the location of the actual record in the data file. So, if we want to find the Peopleid (SQL command for the Select Peopleid from people WHERE Name= ' Mike ') that name equals "Mike" records , MySQL is ab
name column, MySQL will sort the name column in the index:For each item in the index, MySQL internally holds a pointer to the location of the actual record in the data file. So if we want to find the name equals "Mike" Record Peopleid (SQL command for "Select Peopleid from people WHERE Name= ' Mike ';" ), MySQL can find the "Mike" value in the index of name, the
completely randomly insert 1000 different name values into the People table. Shows a small portion of the data file where the people table resides:As you can see, the Name column in the data file does not have any definite order. If we create the index of the name column, MySQL will sort the name column in the index:For each item in the index, MySQL internally holds a pointer to the location of the actual record in the data file. So if we want to find the name equals "
Struct in C Language
Struct type definition:
1 struct student2 {3 int id; 4 char name[10];5 6 };
Note: student is a custom data type, not a variable like int, char is a basic data type,
Struct variable definition and reference:
1 struct student 2 {3 int id; 4 char name [10]; 5} mike, lily; // directly define two struct Variables
1 student mike = {123, {'M', 'I', 'k', 'E'}; // define the variabl
". Therefore, if we want to find the peopleid of the record whose name is equal to "Mike" (the SQL command is "Select peopleid FROM people Where name = 'Mike ';"), mySQL can search for the "Mike" value in the name index, and then directly go to the corresponding row in the data file to return the peopleid (999) of the row accurately ). In this process, MySQL onl
in the index:
For each item in the index, MySQL internally stores the "pointer" of the actual record location in a data file for it ". Therefore, if we want to find the peopleid of the record whose name is equal to "Mike" (the SQL command is "SELECT peopleid FROM people WHERE name = 'Mike ';"), mySQL can search for the "Mike" value in the name index, and then
where the actual record is located in a data file ". Therefore, if we want to find the peopleid of the record whose name is equal to "Mike" (the SQL command is "SELECT peopleid FROM people WHERE name = Mike ;"), mySQL can search for the "Mike" value in the name index, and then directly go to the corresponding row in the data file to return the peopleid (999) of
From: xuejinyoulan [add to my favorites]
Source: it168What is a regular expression?A regular expression uses a special symbol pattern as a string in the expression format. It is mainly used to describe and parse text. ManyProgramRegular Expressions are ignored (or not used) by members (or even some good experts). I think this is a shame, because when we solve many problems, regular Expressions often make us feel comfortable. Once you have mastered it, you will find it can solve countless real-
Understanding of the Block concept in Ruby:
In this paper, we give a comparison between JavaScript code block and Ruby code block, the need of friends can refer to the following
The block in Ruby is generally translated into blocks of code, which seems a bit strange at first because there is no such thing in many languages. Actually, it's not bad.
First-class function and Higher-order function
The first-class function and the Higher-order function are concepts in functional programming langu
The dictionary is the Key-value data typeCreate info = { " stu01 " : " jack " Span style= "COLOR: #000000", " stu02 ": " Mike " ' stu03 " : " View CodeFeatures of the dictionary:
Dict is disordered.
Key must be unique and inherently heavy
Increase>>>info[' stu05 ' = ' kit ' #自动创建 {' stu01 ': ' Jack ', ' stu02 ': ' Mike ', ' stu03 ': ' Jay ', ' stu05 ', ' kit '}By de
a small portion of the data file where the people table resides:As you can see, the Name column in the data file does not have any definite order. If we create the index of the name column, MySQL will sort the name column in the index:For each item in the index, MySQL internally holds a pointer to the location of the actual record in the data file. So if we want to find the name equals "Mike" Record of Peopleid (the SQL command is "Selectpeopleid fro
of the reference type. Why is it a deep copy?
If you look at the source code of the string type, you will know:
// Indicates an empty string. This field is read-only. Public static readonly string Empty;
The answer is that the string type is readonly. When the value of the string type is changed, the memory address will be re-allocated.
Shallow copy: copy a new object to the object.
Definition of shortest copy-only allocates a new memory address for the value type (or string.
Deep copy: copy a
functionCar () {2 }3Car.prototype.color = "Red";4Car.prototype.doors= 4;5car.prototype.mpg= 23;6Car.prototype.showColor =function(){7Alert This. color);8 }9 Ten varOCAR1 =NewCar (); One varOCAR2 =NewCar ();It solves two problems that exist in the previous two ways. But not very satisfactory. First, this constructor has no parameters. When using a prototype, you cannot pass parameters to initialize the value of a property through a constructor, which is annoying but not finished, and the real pr
; post = {"author": "Mike",... "text": "My first blog post!",... "tags": ["mongodb", "python", "pymongo"],... "date": datetime.datetime.utcnow()}
Note: The Python native type can be saved in the file (Datetime. datetime), These types of values are automatically converted between the native type and the bson format. File insertion
You can useInsert ()Method:
>>> posts = db.posts>>> post_id = posts.insert(post)>>> post_idObj
. Consider the following example:Function car (){}Car. Prototype. color = "red ";Car. Prototype. Doors = 4;Car. Prototype. mpg = 23;Car. Prototype. Drivers = new array ("Mike", "Sue ");Car. Prototype. showcolor = function (){Alert (this. Color );}
VaR ocar1 = new car ();VaR ocar2 = new car ();Ocar1.drivers. Push ("Matt ");Alert (ocar1.drivers); // outputs "Mike, Sue, Matt"Alert (ocar2.drivers); // outputs "
1. Prototype chain inheritanceIn order for subclasses to inherit the attributes of the parent class (also including methods), you first need to define a constructor. The new instance of the parent class is then assigned to the constructor's prototype. functionParent(){THIS.name =' Mike '; }functionChild(){This.age =12; } Child.prototype =New Parent (); //child inherits the parent, through the prototype, forms the chain var test = new Child (); aler
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