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this post was submitted on 31 Aug 2023
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Programming
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The unnamed language that is compiled by
cc.To elaborate... C[++] is really two different languages, with mostly distinct feature sets, handled in most cases by different compilers, interpreters, parsers, etc.
The unnamed language with keywords like
#ifdefand#includewhich produces text output is a templating system that is functionally independent of the unnamed language with keywords likeforandunsignedwhich actually compiles to a binary.You can use
cppto run all the logic and conditionals in that first language to produce output, even if you replace the second language with something else like python or assembly.You can use
ccto compile that second language from source to binary, without support from the preprocessor.That second language, the one that
ccunderstands and compiles, does not have the ability to import functions or values or whatever from other files.I'd argue that's not true. That's what the extern keyword is for. If you do
#include, you don't get the actualprintffunction defined by the preprocessor. You just get an extern declaration (though extern is optional for function signatures). The preprocessed source code that is fed toccis still not complete, and cannot be used until it is linked to an object file that definesprintf. So really, the unnamed "C preprocessor output language" can access functions or values from elsewhere.No, it can't. The compiler can't do anything with content from any file not explicitly passed to it. You're mixing up the compiler and the linker (and the linker has nothing to do with either language, it can link binaries compiled from any language).
Holy shit this is fascinating!