Underscores can be used in identifiers in C language, and the main purpose is to distinguish identifiers from implied uses. Start with a single underscore to represent internal variables, and start with a double underscore to represent special identifiers. The rational use of underscores can help improve code standardization, readability and maintainability.

Can C language user identifiers be underlined? Yes, and it's used a lot! But this is not something that can be used casually, there are many ways to do it.

We broke this article and talked about the things underlined in the identifier in C language. After reading it, you can use underscores gracefully like a veteran to write code that is both efficient and easy to read.

Let’s talk about the conclusion first: It can be used! But how to use it and where to use it depends on it. In an identifier, underscore plays two main roles: one is to distinguish identifiers, and the other is to imply the purpose of the identifier.

Naming rules for identifiers

The C language naming rules for identifiers are actually quite loose. Letters, numbers, and underscores are used casually, but they must start with letters or underscores. This gives us a lot of freedom, but it also brings the risk of chaos. So, we have to make a convention and use some skills.

For example, my_variable and myVariable can be used, but the styles are very different. The former uses underscore to divide words, while the latter uses the camel nomenclature. Which one is better? It depends on the team's coding specifications, there is no absolute good or bad, but it is very important to maintain consistency. Teams use hump, you don't use underscores, and vice versa. The code style is consistent and it is comfortable to read.

The special meaning of underscore in identifiers

Underscores are not just about splitting words. Many times, it implies the use of the identifier. For example, an identifier ( _myVariable ) starting with a single underscore usually means that this is an internally used variable and is not recommended to access directly in other modules or files. This is a conventional approach that can improve the maintainability of the code. The compiler won't enforce this convention, but observing it can avoid a lot of unnecessary trouble.

For example, an identifier that starts and ends with a double underscore ( __myVariable__ ) usually means that this is a special identifier defined by the compiler or standard library, so you'd better not touch it. This is not a suggestion, but a warning! Change these identifiers at the least, the compilation error may occur, and the program may crash at the worst.

Some experiences

I have seen a lot of codes, and the underscores are used in a mess, so it makes you feel a headache when you look at them. In order to pursue simplicity, some programmers abbreviate variable names to the extreme and then use underscores to piece together. As a result, the code is obscure and bugs are flying everywhere. This is not a good habit.

Remember, the code is written for people to see, and the second is executed for machines. Clear and easy-to-understand code is not only easy to maintain, but also easier to debug. So, choose the right naming style and use underscores reasonably to make your code more elegant.

Code example (using underscores to distinguish variables)

 <code class="c">#include <stdio.h> int main() { int user_id; // 用戶ID int user_age; // 用戶年齡float user_score; // 用戶分數(shù)printf("請輸入用戶ID，年齡和分數(shù)：\n"); scanf("%d %d %f", &user_id, &user_age, &user_score); printf("用戶ID: %d\n", user_id); printf("用戶年齡: %d\n", user_age); printf("用戶分數(shù): %.2f\n", user_score); return 0; }</stdio.h></code>

In this example, the words are divided by underscores to make the variable name clearer. This is easier to understand than userid , userage , userscore , right?

Guide to the pit

Remember, although underscores are good, don’t use them indiscriminately. Avoid the following:

• Don't overuse underscores, otherwise the code will appear verbose.
• Do not use multiple consecutive underscores in the identifier, which will reduce the readability of the code.
• Do not modify identifiers that start and end with double underscores at will.

In short, mastering the usage of underscores in C language identifiers can help you write more standardized, easier to read, and easier to maintain. This is not only a grammar problem, but also a reflection of programming literacy.

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