Initial data commit

Task/Call-a-foreign-language-function/Crystal/call-a-foreign-language-function.crystal

@@ -0,0 +1,12 @@
+@[Link("c")] # name of library that is passed to linker. Not needed as libc is linked by stdlib.
+lib LibC
+  fun free(ptr : Void*) : Void
+  fun strdup(ptr : Char*) : Char*
+end
+
+s1 = "Hello World!"
+p = LibC.strdup(s1) # returns Char* allocated by LibC
+s2 = String.new(p)
+LibC.free p # pointer can be freed as String.new(Char*) makes a copy of data
+
+puts s2