a.cpp:25:37: warning: array subscript is of type 'char'[-Wchar-subscripts]while(i<s.size()&&isalphanum[s[i]]==0)i++;^~~~~
a.cpp:27:41: warning: array subscript is of type 'char'[-Wchar-subscripts]for(j=i+1;j<s.size()&&isalphanum[s[j]]==1;j++);^~~~~2 warnings generated.