Eroare de compilare: user.cpp: In function ‘void adauga(int, int)’: user.cpp:17: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void sterge(int, int)’: user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int numar(int, int)’: user.cpp:55: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void prefix(int, int)’: user.cpp:68: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:82: error: ‘strlen’ was not declared in this scope