| ... | ... | @@ -38,4 +38,23 @@ How to do it well |
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### Conditional compilation
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"Conditional compilation" in short is what its name suggests: compile depending on a condition. There are two ways to do this:
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- Include <stdlib.h> (this is important!) and use `getenv()`. For example:
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```
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if (getenv("INPUT")) {
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freopen(getenv("INPUT"), "r", stdin);
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freopen(getenv("OUTPUT"), "w", stdout);
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} // if
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```
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- You can also use compiler guards. You may have seen this before in header guards in the form of `#ifndef PATH_TO_FILE`. You can read more about it [here](https://msdn.microsoft.com/en-us/library/ew2hz0yd.aspx). On Mac OS, the operating system macro is `__APPLE__`
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```
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#ifdef __APPLE__
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freopen(“inputFilename.txt”, “r”, stdin);
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freopen(“outputFilename.txt”, “w”, stdout);
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#endif
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```
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### Using environment variables |
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\ No newline at end of file |
