foo.c: In function 'main':
foo.c:10:2: warning: statement with no effect [-Wunused-value]
  for(x;x>0;x/=10){
  ^~~
foo.c:8:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&x);
     ^~~~~~~~~~~~~~
foo.c:12:6: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
   sum=sum+t;
   ~~~^~~~~~

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