Header files inclusion and performance considerations c++ -

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assuming headers have include guards set appropriately, there means of improving run time performance of application altering these headers?

is there difference, performance wise, between application has needed headers in 1 file , application doesn't?

run-time efficiency

the sets of headers included or not included have no effect on efficiency of resulting application @ run time. should include headers declare functions use. if headers provide inline function definitions, example, may performance boost comparison (hypothetical alternative) headers don't provide inline function declarations, still need include header controlled people providing headers.

compile-time efficiency

i first assumed you're after, in part because of mention of header include guards purely compilation-related issue.

if headers set include guards, can still improve efficiency of compilation (with no effect on product) following rules below:

  • don't include same header twice @ source code level.

    #include <stdio.h>  ...40 other project specific includes...  #include <stdio.h>

    (yes, i've seen in real code; i've fixed it, often. and, noted in comments, isn't incredibly bad performance issue, messy in code.)

  • don't include headers aren't needed.


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