+= fib_tail_rec

Lectures/09/Makefile

+OPT = "-O3"
+
 fib: fib.c test_fib.c
 	cc -o test_fib.o -c test_fib.c
-	cc -o fib.o -c fib.c
+	cc $(OPT) -o fib.o -c fib.c
 	cc test_fib.o fib.o -o fib
 
 fib_rec: fib_rec.c test_fib.c
 	cc -DNDEBUG -o test_fib.o -c test_fib.c
-	cc -o fib_rec.o -c fib_rec.c
+	cc $(OPT) -o fib_rec.o -c fib_rec.c
 	cc test_fib.o fib_rec.o -o fib_rec
 
+fib_tail_rec: fib_tail_rec.c test_fib.c
+	cc -DNDEBUG -o test_fib.o -c test_fib.c
+	cc $(OPT) -o fib_tail_rec.o -c fib_tail_rec.c
+	cc test_fib.o fib_tail_rec.o -o fib_tail_rec
+
 fib_dp: fib_dp.c test_fib.c
 	cc -DNDEBUG -o test_fib.o -c test_fib.c
-	cc -o fib.o -c fib_dp.c
+	cc $(OPT) -o fib.o -c fib_dp.c
 	cc test_fib.o fib.o -o fib_dp
 
 fib_lv: fib_lv.c test_fib.c
 	cc -DNDEBUG -o test_fib.o -c test_fib.c
-	cc -o fib.o -c fib_lv.c
+	cc $(OPT) -o fib.o -c fib_lv.c
 	cc test_fib.o fib.o -o fib_lv
 
-all: fib fib_rec fib_dp fib_lv
+all: fib fib_rec fib_tail_rec fib_dp fib_lv
 
 clean:
 	rm *.o
 	rm fib
 	rm fib_rec
+	rm fib_tail_rec
 	rm fib_dp
 	rm fib_lv

Lectures/09/fib_tail_rec.c

+#include <stdio.h>
+#include <stdlib.h>
+
+#include "test_fib.h"
+
+unsigned int fib_rec(unsigned int i, unsigned int a, unsigned int b)
+{
+    if (i == 0)
+    {
+        return a;
+    }
+    else
+    {
+        return fib_rec(i - 1, b, a + b);
+    }
+}
+
+unsigned int fib(unsigned int n)
+{
+    return fib_rec(n, 0, 1);
+}
+
+int main(int argc, char **argv)
+{
+    test_fib();
+    if (argc != 2)
+    {
+        printf("Usage: fib <number>\n");
+        return 1;
+    }
+
+    unsigned int n = atoi(argv[1]);
+
+    unsigned int f = fib(n);
+    printf("fib(%d) = %d\n", n, f);
+}