I have some questions about some APIs in php, please give me some advice.

1: There are some APIs in PHP that I don’t know how to use, and I don’t know what scenarios are most suitable for them. Whether it’s parameters or return values, I don’t understand them all. Don’t ask me to read the manual. I’ve read a lot of manuals. All over. For example, what can pack be used for? It's a big headache. There are really many APIs like this that I don’t quite understand the applicable scenarios. Please give me some guidance.

2: php://stdin, php://stdout, php://input are difficult to understand. I really don’t know what they refer to. Please make it easier to understand.

3: Asking a question, it’s a bit superficial. Many reversible encryption algorithms written convert the string into binary and perform bit operations with the secret key. Finally, the encrypted string is obtained, and then the encrypted string is converted into binary. Operate with the secret key to get the real string. I just want to know, why do you have to convert it to binary? Why do you have to convert it to binary? why? I don't understand. Binary bit operations look too awkward! ! ! !

4: Many frameworks have some raw methods, which probably do not output http headers. What can this method be used for? I don’t understand

5: One last question. A problem with event monitoring. I have never been exposed to the design of event monitoring. Please tell me about it. It can probably be bound to certain instances, monitor certain methods, and execute it according to the situation. Please give me some information or specific instructions on how to design this module.

Actually, there are still some things that I don’t quite understand, so I won’t go into details here. When will I find out again and bring it up again

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1: There are some APIs in PHP that I don’t know how to use, and I don’t know what scenarios are most suitable for them. Whether it’s parameters or return values, I don’t understand them all. Don’t ask me to read the manual. I’ve read a lot of manuals. All over. For example, what can pack be used for? It's a big headache. There are really many APIs like this that I don’t quite understand the applicable scenarios. Please give me some guidance.

2: php://stdin, php://stdout, php://input are difficult to understand. I really don’t know what they refer to. Please make it easier to understand.

3: Asking a question, it’s a bit superficial. Many reversible encryption algorithms written convert the string into binary and perform bit operations with the secret key. Finally, the encrypted string is obtained, and then the encrypted string is converted into binary. Operate with the secret key to get the real string. I just want to know, why do you have to convert it to binary? Why do you have to convert it to binary? why? I don't understand. Binary bit operations look too awkward! ! ! !

4: Many frameworks have some raw methods, which probably do not output http headers. What can this method be used for? I don’t understand

5: One last question. A problem with event monitoring. I have never been exposed to the design of event monitoring. Please tell me about it. It can probably be bound to certain instances, monitor certain methods, and execute it according to the situation. Please give me some information or specific instructions on how to design this module.

Actually, there are still some things that I don’t quite understand, so I won’t go into details here. When will I find out again and bring it up again

1. Don’t ask about usage scenarios. Practice is the standard of truth. Just talking on paper is useless. What we tell you can only be the same as what is said in the manual. To truly understand, you have to learn through practice. Once you have encountered it and used it, you will naturally understand.

2. Streams are the most commonly used form in programming. I believe there are many manuals about the specific meanings of these streams. The key is not how we explain it, but whether you have used it. No matter how easy-to-understand the statement is, it is empty talk if you have never seen it. It's like a blind man touching an elephant. No matter how you describe it, you can't tell the blind man what the elephant looks like.

3. Bit operations are originally for binary. What is binary bit operations? It seems too confusing. Furthermore, all data stored in the computer is binary, whether it is converted or not, it is still binary. The conversion you see is not to binary, to be precise, it is to a unified form. In addition, as a programmer, don't reject it. Why is binary difficult? Just overcome it. It doesn’t matter if it’s difficult or not.

4. raw does not output HTTP headers. Without HTTP headers, it is not called HTTP. HTTP must have a header and may not have a body. It's just like a human being. You can lose arms, but you can't lose your head. Methods such as raw only convert the information in HTTP into a data structure for container operation according to rules, or vice versa.

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