Why the generated C codes have "b_"?

Hello everyone,

Just new to the forumn, please forgive me if i raised up the question in an improper way.

Recently, I am using MATLAB coder to generate C codes. But in the generated codes, I realilzed that some variables have b_ prefix.

For example.

start_point = 1; % this is start_point

Then, the generated codes would look like:

/*  this is start_point */
int b_start_point = 1; 

I am not pretty sure why the varialbe "start_point " has "b_" in front of the variable. Since it is the first time that it is defined, and also, there is no "start_point" in the C code, which means that it is not already exist.

Anyone can give me some clue about why it happens?

Thanks a lot.

[Ryan Wang]

it is possible due to variable name clash. That matlab coder has to rename that variable to ensure it is building successfully. NOT sure myself...

[Vibhav]

Same thing happening with me, I think this has something to do with whether the maximum stack usage is surpassed or not. I noticed that when my code uses less stack space, the function is named without a b_ in front of the actual function name. Haven't found any documentation regarding this naming, so not sure what's happening here.

[Umar]

Hi @ Hao Yan,

The "b_" prefix in variable names is added to prevent naming conflicts with existing variables in the generated C code. This prefix ensures that the generated code remains free from naming collisions, especially when interfacing with other code modules or libraries. By prefixing variables with "b_", MATLAB Coder helps maintain code integrity and avoids unintended variable shadowing or redefinition issues. Please let me know if you have any further questions.

Answer 1

[Arjun]

Hi,

As per my understanding, when you generate code using MATLAB Coder then some of your variables have a “b_” prefix. I tried to do the same on my computer and went through the documentation, my analysis is that while converting code from MATLAB to C/C++ there are many new variables introduced during the process and hence there can be naming conflicts. Some of the probable reasons can be follows:

• Naming Conflicts: If the variable name conflicts with any other variable, functions, reserved words.
• Internal Variables: MATLAB Coder might use prefixes like b_ to distinguish between different types of internal variables or to maintain a consistent naming convention throughout the generated code. It may be used to prevent variable shadowing as well.

I could not find any clear reasoning even after going through the documentation, but some findings are that:

• By default, when possible, variables share names and memory in the generated code.
• The code generator reuses your variable names for other variables or reuses other variable names for your variables.
• The code generator preserves your function name and comments. When possible, the code generator preserves your variable names.

I found something which can help in preserving variable name and you must give it a try:

• In a code generation configuration object, set the PreserveVariableNames parameter to 'UserNames'.
• In the MATLAB® Coder™ app, set Preserve variable names to User names.

https://www.mathworks.com/help/coder/ug/preserve-variable-names-in-generated-code.html

I hope this will help!

[Andrei Gherghescu]

Faced same issue, tried your suggestion but it doesn't work. I am using

// MATLAB Coder version : 23.2