/in/foo.c: In function 'main':
/in/foo.c:23:9: warning: 'b' may be used uninitialized [-Wmaybe-uninitialized]
   23 |         printf("%.2f\n",b);
      |         ^~~~~~~~~~~~~~~~~~
/in/foo.c:4:18: note: 'b' was declared here
    4 |         double a,b;
      |                  ^