less cumbersome string approach for struct

Author: scivision

src/c/struct_lib.c

@@ -7,7 +7,6 @@ struct params {
   // order and lengths must match in Fortran and C
   int my_int;
   bool my_bool;
-  int Lmy_char;
   char my_char[1000];
 };
 
@@ -25,12 +24,7 @@ if (! s.my_bool) {
   exit(EXIT_FAILURE);
 }
 
-if (s.Lmy_char != 5) {
-  fprintf(stderr, "Error: my_char wrong length %d\n", s.Lmy_char);
-  exit(EXIT_FAILURE);
-}
-
-if (strcmp(s.my_char, "Hello") != 0) {
+if (strncmp(s.my_char, "Hello", 5) != 0) {
   fprintf(stderr, "Error: my_char != Hello: %s\n", s.my_char);
   exit(EXIT_FAILURE);
 }

src/c/struct_main.c

@@ -2,12 +2,13 @@
 #include <string.h>
 #include <stdlib.h>
 
+enum { Lchar = 1000 };
+
 struct params {
   // order and lengths must match in Fortran and C
   int my_int;
   bool my_bool;
-  int Lmy_char;
-  char my_char[1000];
+  char my_char[Lchar];
 };
 
 extern void struct_check(struct params *);
@@ -19,7 +20,6 @@ struct params s;
 s.my_int = 123;
 s.my_bool = true;
 strcpy(s.my_char, "Hello");
-s.Lmy_char = strlen(s.my_char);
 
 struct_check(&s);
 

src/cxx/struct_lib.cxx

@@ -6,11 +6,10 @@ struct params {
   // order and lengths must match in Fortran and C
   int my_int;
   bool my_bool;
-  int Lmy_char;
   char my_char[1000];
 };
 
-void struct_check(struct params);
+extern "C" void struct_check(struct params);
 
 void struct_check(struct params s) {
 
@@ -24,12 +23,7 @@ if (! s.my_bool) {
   exit(EXIT_FAILURE);
 }
 
-if (s.Lmy_char != 5) {
-  std::cerr << "Error: my_char wrong length " << s.Lmy_char << std::endl;
-  exit(EXIT_FAILURE);
-}
-
-if (strcmp(s.my_char, "Hello") != 0) {
+if (strncmp(s.my_char, "Hello", 5) != 0) {
   std::cerr << "Error: my_char != Hello " << s.my_char << std::endl;
   exit(EXIT_FAILURE);
 }

src/cxx/struct_main.cxx

@@ -5,7 +5,6 @@ struct params {
   // order and lengths must match in Fortran and C
   int my_int;
   bool my_bool;
-  int Lmy_char;
   char my_char[1000];
 };
 
@@ -18,7 +17,6 @@ struct params s;
 s.my_int = 123;
 s.my_bool = true;
 strcpy(s.my_char, "Hello");
-s.Lmy_char = strlen(s.my_char);
 
 struct_check(&s);
 

src/fortran/struct_lib.f90

@@ -9,7 +9,6 @@ module struct_rx
 !! order and length must match in Fortran and C
 integer(c_int) :: my_int
 logical(c_bool) :: my_bool
-integer(c_int) :: Lmy_char
 character(kind=c_char) :: my_char(1000)
 !! character(kind=c_char) in bind(c) type cannot be allocatable. Just have to make it "long enough"
 !! or use iso_c_binding.h stuff
@@ -28,18 +27,17 @@ pure subroutine struct_check(s) bind(C)
 
 if(s%my_int /= 123) error stop "my_int /= 123"
 if(.not. s%my_bool) error stop "my_bool /= .true."
-if(s%Lmy_char /= 5) error stop "Lmy_char /= 5"
 
 block
-  character(s%Lmy_char) :: buf
+  character(size(s%my_char)) :: buf
   integer :: i
   buf = "" !< ensure buf has no garbage characters
 
-  do i = 1, s%Lmy_char
+  do i = 1, len(buf)
     if (s%my_char(i) == c_null_char) exit
     buf(i:i) = s%my_char(i)
   enddo
-  my_char = buf
+  my_char = trim(buf)
 end block
 
 if(my_char /= "Hello") error stop "my_char /= 'Hello'"

src/fortran/struct_main.f90

@@ -9,7 +9,6 @@ program struct_tx
 !! order and length must match in Fortran and C
 integer(c_int) :: my_int
 logical(c_bool) :: my_bool
-integer(c_int) :: Lmy_char
 character(kind=c_char) :: my_char(1000)
 !! character(kind=c_char) in bind(c) type cannot be allocatable. Just have to make it "long enough"
 !! or use iso_c_binding.h stuff
@@ -34,13 +33,13 @@ end subroutine struct_check
 
 s%my_int = 123
 s%my_bool = .true.
-s%Lmy_char = len(my_char)
 
-do i = 1, s%Lmy_char
+do i = 1, len(my_char)
   s%my_char(i) = my_char(i:i)
 end do
 s%my_char(i+1) = c_null_char
 
+call struct_check(s)
 
 print *, "OK: Fortran => C struct"
 end program