Eroare de compilare: user.cpp: In function ‘int main(int, char**)’: user.cpp:9: error: ‘fopen’ was not declared in this scope user.cpp:11: error: ‘fscanf’ was not declared in this scope user.cpp:12: error: ‘fclose’ was not declared in this scope user.cpp:17: error: ‘fprintf’ was not declared in this scope user.cpp:24: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result