/in/foo.cc: In function 'int main()':
/in/foo.cc:9:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<strlen(a);i++){
                ^
/in/foo.cc:23:8: warning: statement has no effect [-Wunused-value]
   for(j;j>=0;j--) cout<<b[j];
        ^