L-40 MCS 275 Wed 18 Apr 2001

/* L-40 MCS 275 Wed 18 Apr 2001 : illustration of the make utility. */

/* Suppose we wish to create a program to compute the Fibonacci
   numbers once iteratively and once recursively.
   The program below is the main program that calls "Fib".
   There are two different implementations of "Fib", the
   recursive one is in the file fibrec.c, the iterative one
   is in the file fibitr.c.  With "make" we create two different
   executable main programs : fbwrec and fbwitr. */

#include <stdio.h>

extern int Fib ( int n );
/* returns the n-th Fibonacci number */

int main ()
{
   int n;

   printf("\nCalculation of Fibonacci numbers\n");
   printf("Give a natural number : "); scanf("%d",&n);
   printf("Fibonacci number #%d is %d.\n",n,Fib(n));

   return 0;
}

/* recursive implementation of the calculation of Fibonacci numbers */

int Fib ( int n )
{
   if (n == 0 || n == 1)
      return 1;
   else
      return Fib(n-1) + Fib(n-2);
}

/* iterative implementation of the calculation of Fibonacci numbers */

int Fib ( int n )
{
   int previous,current,temp,i;
   previous = 1;
   current = 1;
   for (i = 1; i < n; i++)
   {
      temp = previous + current;
      previous = current;
      current = temp;
   }
   return current;
}

# Illustration of make file to create different executables from
# one main program with different versions of subroutines.
# All intendations at beginning of line are TABs.
# To create the executable programs, type "make fbwrec", and
# "make fbwitr", for the respective recursive and iterative versions.
# Type "make all" to create everything.
# With "make clean" we clean up all object files and executables.

# compiler directives :

compile = gcc -c
link = gcc -o

# recursive and iterative versions of Fibonacci function :

fibrec.o: fibrec.c
	@echo compiling fibrec
	@$(compile) fibrec.c

fibitr.o: fibitr.c
	@echo compiling fibitr
	@$(compile) fibitr.c

# main program :

fibmain.o: fibmain.c
	@echo compiling fibmain
	@$(compile) fibmain.c

# the executables :

fbwrec: fibrec.o fibmain.o
	@echo linking...
	@$(link) fbwrec fibrec.o fibmain.o
	@echo done, executable is in fbwrec

fbwitr: fibitr.o fibmain.o
	@echo linking...
	@$(link) fbwitr fibitr.o fibmain.o
	@echo done, executable is in fbwitr

fib: fibrec.c fibmain.c
	gcc -p fibrec.c fibmain.c

# make the versions with the profiler :

pfbwrec: fibrec.c fibmain.c
	cc -p -o pfbwrec fibrec.c fibmain.c

pfbwitr: fibitr.c fibmain.c
	cc -p -o pfbwitr fibitr.c fibmain.c

# making everything :

all: fbwrec fbwitr pfbwrec pfbwitr

# clean up the directory

clean:
	@echo cleaning object files and executables
	@/bin/rm -f -r *o fbwrec fbwitr pfbwrec pfbwitr