Eroare de compilare: user.cpp: In function ‘int retine(int)’: user.cpp:28: error: ‘fprintf’ was not declared in this scope user.cpp:29: error: ‘fprintf’ was not declared in this scope user.cpp:30: warning: no return statement in function returning non-void user.cpp: In function ‘void back(int)’: user.cpp:38: warning: suggest explicit braces to avoid ambiguous ‘else’ user.cpp: In function ‘int main()’: user.cpp:48: error: ‘fopen’ was not declared in this scope user.cpp:50: error: ‘fscanf’ was not declared in this scope user.cpp:52: error: ‘fclose’ was not declared in this scope