Import official C23 code examples for Modern C (Jens Gustedt, 2024)HEADupstream-importmain

- Add official C source files, Makefile, c23-fallback.h, and LICENSE
- Update README.md with study mirror notice

1 files changed, 30 insertions, 0 deletions

diff --git a/array_or_struct.c b/array_or_struct.c
new file mode 100644
index 0000000..3190fe1
--- /dev/null
+++ b/array_or_struct.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+
+#ifdef USE_STRUCT
+  typedef struct two two;
+  struct two { double e1; double e2; };
+# define FRST(X) ((X).e1)
+# define SEC(X) ((X).e2)
+#else
+  typedef double two[2];
+# define FRST(X) ((X)[0])
+# define SEC(X) ((X)[1])
+#endif
+
+void func0(void) {
+  for (two sp = { 1, 1, };
+       FRST(sp) + SEC(sp) < 10;
+       FRST(sp) += SEC(sp)) {
+    printf("two values %g %g\n", FRST(sp), SEC(sp));
+    SEC(sp) += (FRST(sp) + SEC(sp))/2;
+  }
+}
+
+void func1(void) {
+  for (register two sp = { 1, 1, };
+       FRST(sp) + SEC(sp) < 10;
+       FRST(sp) += SEC(sp)) {
+    printf("two values %g %g\n", FRST(sp), SEC(sp));
+    SEC(sp) += (FRST(sp) + SEC(sp))/2;
+  }
+}