Summary of \ r and \ n

Summary of \ r and \ n

\ R indicates carriage return and \ n indicates line feed. In Windows, the input key will automatically become \ r \ n.

In Windows, \ r \ n is also required for line breaks. Why do we need two characters? Because Windows adopts the traditional typewriter model, there is a small story:

Before the computer appeared, there was a kind of device called Teletype Model 33, which can contain 10 characters per second. But there is a problem, that is, when a line breaks a line, it takes 0.2 seconds, just two characters. If a new character is passed in the 0.2 s, the character will be lost.

As a result, the developers thought of a way to solve this problem, that is, adding two end characters after each line. One is "Press ENTER", which tells the typewriter to position the print head on the left border (the first line of the line), and the other is "line feed", which tells the typewriter to move the paper down one line.

This is the source of "line feed" and "Carriage Return". They can also be seen in their English names.

Later, computers were invented, and these two concepts were invented on computers. At that time, memory was very expensive. Some scientists thought it would be too waste to add two characters at the end of each line. Just add one character. As a result, there were differences.

In Unix systems, each line ends with "<line feed>", that is, "\ n". In Windows systems, each line ends with "<line feed> <press enter> ", that is, "\ n \ r". In Mac systems, the end of each line is "<press enter> ". One direct consequence is that if a file in Unix/Mac is opened in Windows, all the text will be changed to a line; if a file in Windows is opened in Unix/Mac, A ^ M symbol may be added at the end of each line.

However, there are many editors, such as Editplus and Notepad, which can also be used for line breaks for writing such as \ r and \ n, but if it is opened in Windows Notepad, newline can only be entered in the form of \ r \ n.

In addition, in Windows notepad, \ r should be used separately to return to the beginning of the line, but it is the same as useless. Using \ n alone won't work.

The explanation on the Internet is also true.

In Windows:

'\ R': Press enter to return to the beginning of the current row, instead of switching to the next row;

'\ N' line feed, switch to the next line at the current position, instead of returning to the first line;

Why is it ineffective to use it independently? Does it mean that separate use is meaningless?

Summary of some questions about the camera our midterm exam, the teacher gave us a question so that we can find the answer as much as possible

The indoor light is dark, the shutter speed is low, and the jitter causes blur. One method is to use a flashlight, and the other is to use a tripod. 2. Reduce the aperture and increase the depth of field. 3. The difference is clear, not dynamic, fuzzy, and dynamic.

Summary of high school mathematics knowledge points

Summary of high school mathematics knowledge points
1. For a set, it is necessary to grasp the representative elements of the Set and the "certainty, interoperability, and disorder" of the elements ".

What each element represents?

Focus on the collection of digital axes and wens' diagrams.
An empty set is a subset of all sets and a true subset of all non-empty sets.

3. Pay attention to the following attributes:

(3) Morgan's Law:

4. Will you use the makeup idea to solve the problem? (Exclusion and indirect)

.

6. What are the four forms of propositions and their relationships?
(The proposition of the inverse relation is equivalent .)
The original and inverse propositions are the same as true and false, and the inverse and negative propositions are the same as true and false.
7. Do you understand the concept of ing? Ing f: A → B. Do you notice the arbitrariness of elements in A and the uniqueness of corresponding elements in B?
(One-to-one, multiple-to-one, allowing Element B to have no original image .)
8. What are the three elements of a function? How do I compare whether two functions are the same?
(Defined domain, corresponding rule, value range)
9. What are the common types of definition fields of functions?

10. How do I find the definition fields of composite functions?

Which of the following is the domain name _____________.

11. When I find an analytical expression of a function or an inverse function of a function, do I specify the definition field of the function?

12. What are the conditions for the existence of the antifunction?
(One-to-one correspondence function)
Have you mastered the steps for finding the inverse function?
(① Reverse solution x; ② interchange x and y; ③ specifying the definite domain)

13. What are the properties of the antifunction?
① An image of reciprocal functions is symmetric with a straight line y = x;
② Saves the monotonic and odd functions of the original functions;

14. How can I use definitions to prove the monotonicity of a function?
(Value, difference, positive and negative)
How can we determine the monotonicity of a composite function?

......)
15. How can I use the derivative to determine the monotonicity of a function?

The value is ()
A. 0B. 1C. 2D. 3

The maximum value of limit a is 3)
16. What are the necessary (inadequate) Conditions for function f (x) To be parity?
(F (x) definite domain about symmetric origin)

Note the following conclusions:
(1) In the public definition domain: the product of two odd functions is an even function; the product of two even functions is an even function; and the product of one odd function is a strange function.

17. Are you familiar with the definition of cyclic functions?

Function, T is a cycle .)

For example:

18. Have you mastered common image transformations?

Note the following "fold" Conversion:

19. Are you familiar with the images and Properties of common functions?

.

Application: ① relationship of "Three quadratic" (quadratic function, quadratic equation, quadratic inequality) -- quadratic equation

② Calculate the maximum value on the closed interval [m, n.
③ Calculate the maximum value of interval (dynamic) and symmetric axis (dynamic.
④ Distribution of root of a quadratic equation.

Recorded by images! (Pay attention to the limit on the base number !)

What is the difference between finding the greatest value using its monotonicity and using the mean inequality?

20. Do you often encounter errors in basic operations?

21. How to Solve the abstract function problem?
(Value assignment and structure transformation)

22. Have you mastered the common methods for finding the function value range?
(Quadratic function method (formula method), inverse function method, substitution method, Mean Theorem method, discriminant method, monotonic function method, derivative method, etc .)
Calculate the maximum value of the following functions:

23. Do you remember the radian definition? Can I write the arc-length and slice-area formulas with a circle center angle of α and a radius of R?

24. Familiar with the definition of trigonometric function, the definition of trigonometric function line in the Unit Circle

25. Can you quickly draw a sine, cosine, and tangent function image? Does the image write the monotonic interval, symmetric point, and symmetric axis?

(X, y) is used as an image.

27. When finding an angle in a trigonometric function, pay attention to two aspects: first obtain a trigonometric function value and then determine the angle range.

28. When solving the problem that contains the positive and Cosine Functions, you should note... the remaining full text>