Rakefile

print_reverse.c

#include<stdio.h>
#include<string.h>

void print_reverse(char *s)
{
  size_t len = strlen(s);
  char *t = s + len - 1;

  while (t >= s){
    printf("%c", *t);

    t = t - 1;
  }
  puts("");
}


int main(void)
{
  char word[80];
  printf("逆順に表示する文字列：");
  fgets(word, 80, stdin);
  print_reverse(word);
  return 0;
}

Rakefile

CC = "gcc"

task :default => "print_reverse"

file "print_reverse" => "print_reverse.o" do
  sh "#{ CC } -o print_reverse print_reverse.o"
end

file "print_reverse.o" => "print_reverse.c" do
  sh "#{ CC } -c print_reverse.c"
end