Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:13: warning: format ‘%s’ expects type ‘char*’, but argument 2 has type ‘char (*)[21]’ user.cpp:20: error: ‘strlen’ was not declared in this scope user.cpp:10: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:13: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:17: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result