GNU Make: Remove string from array with subdirectories if string contains "dirToExclude"

Question

I have a directory with a lot of subdirectories which are containing source-files. Therefore I am looking in every subdirectoy for.c-files: cSources = $(shell dir /s /b *.c)

However there are subdirectories with source-files I do not want to compile. If I have a variable dirToExclude = dirName how can I remove every string in cSources that contains 'dirName'?

I know that there is the findstring -function. But I can't figure out how to use findstring on every string in the array. I am looking for some way to get a nested loop like (pseudo code):

foreach (var in cSources)
   if (var.contains(dirToExclude))
       cSources -= var
   endif

Answer 1

If you know dirToExclude is always at the beginning of the string you can just write:

cSources := $(filter-out $(dirToExclude)%,$(cSources))

If you want to remove any filename where the string appears anywhere, you can use:

cSources := $(foreach S,$(cSources),$(if $(findstring $(dirToExclude),$(S)),,$(S)))

See https://www.gnu.org/software/make/manual/html_node/Functions.html