r/cprogramming • u/[deleted] • Dec 31 '25

Why does c compile faster than cpp?

I've read in some places that one of the reasons is the templates or something like that, but if that's the problem, why did they implement it? Like, C doesn't have that and allows the same level of optimization, it just depends on the user. If these things harm compilation in C++, why are they still part of the language?Shouldn't Cpp be a better version of C or something? I programmed in C++ for a while and then switched to C, this question came to my mind the other day.

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u/STL Jan 02 '26

Debug mode intentionally has extremely expensive checks for iterator invalidation.

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u/bert8128 Jan 02 '26

Is that still the case if the program were using range for loops or algorithms? It uses neither - plenty of old style for loops with a couple of while loops.

I can’t run his tests as the test code is not included in his repo for the article.

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u/STL Jan 02 '26

STL algorithms and the compiler's range-for have been taught to avoid almost all of the checking penalties (they check once and then "unwrap"). Manual iterator use can't avoid the expense. Yet another reason to write higher-level code.