foo.cc: In function 'int main()':
foo.cc:23:15: warning: 'n3' may be used uninitialized [-Wmaybe-uninitialized]
   23 |         printf("%.2f",n3);
      |         ~~~~~~^~~~~~~~~~~
foo.cc:5:21: note: 'n3' was declared here
    5 |         float n1,n2,n3;
      |                     ^~

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