/in/foo.cc: In function 'int main()':
/in/foo.cc:8:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<strlen(s);i++)
              ~^~~~~~~~~~
/in/foo.cc:9:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   a[s[i]]++;
         ^
/in/foo.cc:11:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(a[i]!=0)
         ^
/in/foo.cc:10:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(char i='a';i<='z';i++)
  ^~~
/in/foo.cc:13:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
   cout<<endl;
   ^~~~
/in/foo.cc:15:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(a[i]!=0)
         ^
/in/foo.cc:16:13: warning: array subscript has type 'char' [-Wchar-subscripts]
    cout<<a[i];    
             ^