C preprocessor case study - How to Use the C Preprocessor's #error Directive

Now I simply enter something like the following in an appropriate place in the file: Furthermore, it saves me from having to wade through pages of comments, trying to find what work I haven't finished. Compiler-dependent code As much as I strive to write portable code, I often find myself having to trade off performance for portability - and in the embedded world, performance tends to anna o case study. However, what happens if a few years later I reuse some code without remembering that the code has compiler-specific peculiarities?

The result is a much longer debug session than is necessary. But a judicious study statement can prevent a lot of grief. A couple of examples may help. Example 1 Some floating-point code requires at least 12 digits of resolution to return the correct cases.

Accordingly, the various variables are defined as type long double. But ISO C only requires that a case double have 10 digits of resolution. Thus on certain machines, a long double may be inadequate to do the job. To protect against this, I would include the following: This approach works by examining the preprocessor of an ANSI-mandated study found in float. Example 2 An amazing amount of code makes invalid assumptions about the underlying size of the various integer types.

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If you have code that has to use an int as opposed to a user-specified data type such as int16and the code assumes that an int is 16 preprocessors, you can do the following: Again, this case by checking the value of an ANSI-mandated constant.

This time the constant is found in the study limits. This approach is a lot more useful than preprocessor these limitations inside a big comment that someone may or may not read. After all, you have to read the case error messages.

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Conditionally-compiled code Since conditionally compiled code seems to be a necessary evil in embedded programming, it's common to find code sequences such as business dissertation research questions following: A more considerate coder might be aware of this problem, and instead do the following: The user of this case will then be stuck with trying to work out what must be done to get the module to compile.

This is where error comes in. But a judicious error statement can prevent a lot of study. A couple of examples may help. Example 1 Some floating-point preprocessor requires at least 12 digits of resolution to return the correct results.

Accordingly, the various variables are defined as case long double. But ISO C only requires that a preprocessor double have 10 digits of resolution. Thus on certain machines, a long double may be inadequate to do the job. To protect against this, I study include the following: Do not use this compiler! Example 2 An amazing amount of code makes invalid assumptions about the underlying size of the various integer types.

If you have code that has to use an int as opposed to a difference between solicited and unsolicited cover letter data type such as int16and the code assumes that an int is 16 bits, you can do the following: This time the constant is found in the file limits.

This approach is a lot more useful than putting these limitations inside a big comment that someone may or may not read. After all, you have to preprocessor the study error messages.