Compilare: user.cpp: In function ‘int main()’: user.cpp:26:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<a.length(); i+=2){ ^ user.cpp:40:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=2; i<a.length(); i+=2){ ^ user.cpp:59:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<a.length(); i++){ ^ user.cpp:23:9: warning: unused variable ‘temp’ [-Wunused-variable] int temp = a.length(); ^