What are the naming rules for local variables in C language?

Principles of local variable naming in C language: see the name and know the meaning, and clearly express the use and meaning of variables. Use meaningful English words or abbreviations to avoid blur and confusion. Follow the camel or underline nomenclature to keep the style consistent. Avoid single letter variable names unless they are loop counters or temporary variables. Keep naming consistent and do not change it at will. Never use system keywords or reserved words as variable names.

To put it bluntly, the naming of local variables in C language is how to name the little guys inside your function. This seems simple, but it has hidden mystery, which is related to the readability, maintainability, and even performance of the code (although it doesn't have much impact, we are pursuing the ultimate).

Many people think that you can just name it, but the compiler can recognize it anyway. This idea is too naive! Imagine that you are facing a function with thousands of lines of code, with variable names all a , b , c , or var1 , var2 , var3 , and it feels like reading a book of heaven. Debugging is even more of a nightmare.

Therefore, good local variable naming is a compulsory course for programmers. It should clearly express the purpose and meaning of the variable.

Core principle: See the name and know the meaning

This is not just empty talk. A good variable name should let you understand what it is and what it is for at a glance. For example, in the function of calculating the area of ​​a circle, the radius can be used as radius , and the area can be used as area , instead of r and a . Even if you think r and a were very concise at that time, you might forget what they mean by looking at it in a few days.

Some suggestions are not dead rules, but flexible use is the best way:

• Use meaningful English words or abbreviations: userName is better than un , itemCount is better than ic . Make sure that the abbreviation is easy to understand in the context of your code, and don't abbreviate it for the sake of abbreviation and make things worse.
• Follow the camel nomenclature or underscore nomenclature: camelCase is like userName , and underscore nomenclature (snake_case) is like user_name . Choose a style, and stick to it, and don't mix it in a project. I personally prefer hump, which is pleasing to the eye.
• Avoid using single-letter variable names unless they are loop counters or temporary variables: i , j , k are common in loops, and everyone can understand it. But try to avoid other places.
• Keep naming consistency: If you use userName , don't use user_name for a while, username for a while. Keep consistency and make the code look tidy.
• Do not use system keywords or reserved words as variable names: this can cause compilation errors, which is common sense.

Code example:

A function that calculates the average value, compares good naming and bad naming:

 <code class="c">// Bad naming float avg(float a, float b, float c) { float sum = abc; float av = sum / 3; return av; } // Good naming float calculateAverage(float num1, float num2, float num3) { float sumOfNumbers = num1 num2 num3; float average = sumOfNumbers / 3.0f; // 注意这里加了.0f 保证精度return average; }</code>

Have you seen the difference? In the second version, the readability of the code is significantly improved.

Experience in trapping:

Once in a project, the variable naming was not standardized, making it very difficult to maintain later. I spent a lot of time clarifying the meaning of variables and modifying bugs. The lesson is profound! Therefore, it is definitely worth the investment to develop good naming habits from the beginning.

Summarize:

The naming of local variables in C language seems like a small matter, but it actually has a big relationship. Follow the above suggestions and develop good naming habits. Your code will be clearer and easier to maintain, and you will also avoid many detours. Remember, the code is written for people to see, and the second is executed for machines.

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