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, 27 insertions, 0 deletions

diff --git a/fibonacci3.c b/fibonacci3.c
new file mode 100644
index 0000000..2ed77ef
--- /dev/null
+++ b/fibonacci3.c
@@ -0,0 +1,27 @@
+#include "c23-fallback.h"
+#include <stdio.h>
+
+void fib2rec(size_t n, size_t buf[2]) {
+  if (n) {
+    size_t res = buf[0] + buf[1];
+    buf[1] = buf[0];
+    buf[0] = res;
+    fib2rec(n-1, buf);
+  }
+}
+
+
+size_t fib2(size_t n) {
+  size_t res[2] = { 1, 1, };
+  if (n > 2) fib2rec(n - 2, res);
+  return res[0];
+}
+
+int main(int argc, char* argv[argc+1]) {
+  for (int i = 1; i < argc; ++i) {             // process args
+    size_t const n = strtoull(argv[i], nullptr, 0); // arg -> size_t
+    printf("fib(%zu) is %zu\n",
+           n, fib2(n));
+  }
+  return EXIT_SUCCESS;
+}