foo.c: In function 'main':
foo.c:68:2: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
   68 |  printf("%c=%.3lf",x,ans==0?abs(ans):ans);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:30:22: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   30 |     b=(state=='+'?b+t:b-t);
      |       ~~~~~~~~~~~~~~~^~~~~
foo.c:47:21: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   47 |    a=(state=='+'?a+t:a-t);
      |      ~~~~~~~~~~~~~~~^~~~~

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