May I have some questions about some APIs of php?

1: Some APIs in php are not very useful, and I don't know what scenarios are most suitable. whether it is a parameter or a return value, it makes me a little confused. don't tell me the manual, I have read the manual many times. For example, what can pack be used? Big. There are a lot of APIs like this... 1: Some APIs in php are not very useful, and I don't know what scenarios are most suitable. whether it is a parameter or a return value, it makes me a little confused. don't tell me the manual, I have read the manual many times. For example, what can pack be used? Big. Many APIs like this do not really understand the applicable scenarios. Please be a fan of me.

2: php: // stdin, php: // stdout, php: // input, which is difficult to understand. I really don't know what it means. please be easy to understand.

3: to ask a question, it is superficial. many reversible encryption algorithms are written to convert the string into a binary system and perform bitwise operations with the key to obtain the encrypted string, then, the encrypted string is converted into a binary string and the key is calculated to obtain the real string. I want to know, why do I have to convert it to a binary system? Why do we have to convert it to a binary system? Why? I don't know. The bitwise operation in hexadecimal notation looks awkward !!!!

4: There are some raw methods in many frameworks, probably because the http header is not output. What can this method do? Not clear

5: Last question. An event listening problem. I have never touched on the design of event listening. let's talk about how it can be bound to some instances, listen to some methods, and how it works. Please give me some information or how to design this module.

In fact, there are some things that I don't quite understand. I will not go into detail here. When can I find it again?

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1: Some APIs in php are not very useful, and I don't know what scenarios are most suitable. whether it is a parameter or a return value, it makes me a little confused. don't tell me the manual, I have read the manual many times. For example, what can pack be used? Big. Many APIs like this do not really understand the applicable scenarios. Please be a fan of me.

2: php: // stdin, php: // stdout, php: // input, which is difficult to understand. I really don't know what it means. please be easy to understand.

3: to ask a question, it is superficial. many reversible encryption algorithms are written to convert the string into a binary system and perform bitwise operations with the key to obtain the encrypted string, then, the encrypted string is converted into a binary string and the key is calculated to obtain the real string. I want to know, why do I have to convert it to a binary system? Why do we have to convert it to a binary system? Why? I don't know. The bitwise operation in hexadecimal notation looks awkward !!!!

4: There are some raw methods in many frameworks, probably because the http header is not output. What can this method do? Not clear

5: Last question. An event listening problem. I have never touched on the design of event listening. let's talk about how it can be bound to some instances, listen to some methods, and how it works. Please give me some information or how to design this module.

In fact, there are some things that I don't quite understand. I will not go into detail here. When can I find it again?

1. Use cases should not be asked. practice is the standard of truth. It is useless to talk on paper. we can only tell you what we have to say in the manual. we really need to understand it. you need to learn it in practice. Once you have met and used it, you will naturally know.

2. Stream is the most commonly used form in programming. the specific meanings of these streams are also believed in many manuals. The key is not how we explain it, but whether you have used it. You have never seen it before. It's like a blind person's image. you can't tell the blind elephant how to describe it.

3. Bitwise operations are intended to be binary. what is binary bitwise operations seems too awkward. In addition, all the data stored in the computer is binary and is not transferred. The conversion you see is not converted to binary, but to be precise, it is converted to a unified form. In addition, as programmers, do not reject it. it is difficult to conquer binary. You don't have.

4. Raw is not an HTTP header, but an HTTP header. HTTP must have a header and can have no body. This is the same as a human being. you can have less hands, but not no heads. Raw only converts the information in HTTP to the data structure of container operations according to rules, or vice versa.

5. There are many books on design patterns, and there is a lot of information on the Internet.