title: Makefile: ...is up to date
body: <p>I have made a makefile for some c files. I have seen too many ways on the internet but i had always the same problem: make: `q_a' is up to date.</p>
  
  <pre><code>q_a: 
  gcc -o q_a quick_sort_i.c
  
  q_g: 
  gcc -o q_g quick_sort_g.c
  
  s_a: 
  gcc -o s_a shell_sort_i.c
  
  s_g: 
  gcc -o s_g shell_sort_g.c
  
  fork: 
  gcc -o fork fork.c
  </code></pre>
  
  <p>I have not files with the same name in my folder and I can compile them when I write in terminal. Can you help? Thanks in advance! </p>