Preparations before the interview --- C # knowledge Review ---- 03,

Preparations before the interview --- C # knowledge Review ---- 03,

After a day's rush, I have a mixed feeling, not a detail

Let's look back at the title. C # Review of knowledge points

Take a look at the content, database 3NF

Forgive me for this title party

Continue today

1. Differences between Post and Get in HTTP

This is simple. Do you feel excited? After a sigh of relief, you finally have a problem that you can chat for 10 minutes.

According to the HTTP specification, Get is used to obtain information, and should be secure and idempotent. After the parameter is URL? Separated to & connected.

According to the HTTP specification, Post indicates that the server's resource request may be modified. Data exists in the HTTP package

The most basic of the above is to know, the focus is on the emergence of chat, security.

Read: http://www.cnblogs.com/hyddd/archive/2009/03/31/1426026.html for details

Special attention should be paid to the idempotent representation of security and data security, which are two different things. When thoroughly talking with the interviewer about the meaning of the same word under different circumstances, it will make ta think that you have carefully studied this and understood the principle, rather than float and surface.

Add one more question:

Because Get is safe, the content returned by Get can be cached by the browser and Cache server. However, the Cache server does not Cache Post request content, sometimes, when you submit a form and press F5, the index jumps out the confirmation box.

The above sentence can be understood, indicating that you have basically understood Get and Post.

The interviewer will continue to recover the website after all of them go to HTTP.

Difference between UDP and TCP

TCP is a connection-based Protocol. A TCP connection can be established only after three "conversations". The process is very complicated. This is only a simple and visual introduction, because I only understand this process.

Host A said to host B, "can I send data to you ?" This is the first conversation. host a is directed to host B.

Host B replied to A: "Yes. When will you send it ?" This is the second conversation.

Host A said to host B, "I will send it now. Let's proceed !" This is the third dialog; host A is directed to host B.

The purpose of the three "dialogs" is to synchronize the transmission and receipt of data packets. After the three "dialogs", host A formally sends data to host B.

User Data Protocol (UDP) is the Protocol corresponding to TCP. It is a non-connection-oriented protocol. Instead of establishing a connection with the other Party, it directly sends data packets. For example, we call and chat about QQ. You can directly call and send information without the consent of the other party.

Can refer to Baidu: http://baike.baidu.com/link? Url = ZHBJ2gr3HySVVwOYGlqeOQJdeavqBAcDCr7udU7brRyewsTlwGguXZyd3rXZlk6UVdC_Gx-s9RyF57NBHsWI9K

Basically, whether the interviewer continues to expand depends on your answer.

2. How do I determine whether two objects are equal in C?

Isn't it wrong? Is that a problem? To judge equality, You Need To Ask !!! Be careful. This question is too big.

The conditions are Equal to ==, Equal, and ReferenceEquals.

 

ReferenceEquals is a static Object method used to compare whether two variables of the reference type are referenced by the same Object. For the value type, it always returns false.

 

= Is a binary operator that can be overloaded. It can be used to compare whether two objects are equal.
For the built-in value type, = determines whether the values of the two objects are equal. It automatically performs necessary type conversion as needed, and returns true or false based on whether the values of the two objects are equal. For user-defined value types, if the = operator is not overloaded, = is not usable. For the Reference type, = the default behavior is the same as that of ReferenceEquals. true is returned only when two objects point to the same Reference. However, many classes in the. NET Framework overload =. For example, if the = of the String class is the same as the Equals class, determine whether the content of the two strings is equal. Therefore, we recommend that you do not use the = operator for the reference type defined by the system in the application to avoid different running results in the program.

 

The Equals method has different definitions for the value type and reference type. For the value type, the type is the same, and the value is the same (for each struct member, it must be the same), Equals returns true, otherwise, false is returned. For Reference types, the default behavior is the same as that of ReferenceEquals. true is returned only when two objects point to the same Reference.

 

The above are from: http://www.cnblogs.com/zagelover/articles/2741409.html detailed content, click to view, the analysis is very thorough

Deep copy and shallow copy are also mentioned at the end of the article, which is extended by default, but basically returns to the value type and the understanding of the reference type.

Above, continue later