foo.cc: In function ‘int main()’:
foo.cc:30:23: warning: ‘zdxb’ may be used uninitialized [-Wmaybe-uninitialized]
   30 |                 a[zdxb]-=zx;
      |                 ~~~~~~^
foo.cc:16:26: note: ‘zdxb’ was declared here
   16 |                 int zd=0,zdxb,zx=100;
      |                          ^~~~