32 lines
1.2 KiB
Markdown
32 lines
1.2 KiB
Markdown
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+++
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title = "preprocessing"
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draft = false
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tags = [
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"",
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"Users",
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"jefklak",
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"Downloads",
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"pages",
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"code",
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"c",
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"preprocessing"
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]
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date = "2013-12-02"
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+++
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# Preprocessing
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## Handige macro's
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##### Exception/Debug informatie expanden
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```c++
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#define _ERROR_STR2(a) #a
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#define _ERROR_STR(a) _ERROR_STR2(a)
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#define ERROR_INFO(fn) _T(_ERROR_STR(__FILE__" line: "__LINE__" function: "fn))
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```
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Te gebruiken als `someFn(ERROR_INFO("bla"))`. Merk op dat `__FUNCTION__` of `__FUNC__` ook gebruikt kan worden, afhankelijk van de C++ compiler, maar dit is geen deel van de standaard (vanaf C++ v11).
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De `#a` notatie wordt gebruikt om iets te [stringifyen](http://gcc.gnu.org/onlinedocs/cpp/Stringification.html) in de preprocessor, vandaar de delegate:
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> Sometimes you may want to convert a macro argument into a string constant. Parameters are not replaced inside string constants, but you can use the ‘#’ preprocessing operator instead. When a macro parameter is used with a leading ‘#’, the preprocessor replaces it with the literal text of the actual argument, converted to a string constant. Unlike normal parameter replacement, the argument is not macro-expanded first. This is called stringification.
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