Compilare: user.cpp:12:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^ user.cpp: In function ‘int main()’: user.cpp:21:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ( k%2==0 ) { for ( i=0 ; i<=strlen(s)/2 - 1 ; ++i ) ~^~~~~~~~~~~~~~~~~ user.cpp:30:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ( k%2==1 ) { for ( i=0 ; i<=strlen(s)/2 ; ++i ) ~^~~~~~~~~~~~~