Compilare: user.cpp: In function ‘int main()’: user.cpp:24: warning: format ‘%s’ expects type ‘char*’, but argument 2 has type ‘char (*)[30]’ user.cpp:13: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:14: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:12: warning: ‘a’ may be used uninitialized in this function user.cpp:12: warning: ‘c’ may be used uninitialized in this function user.cpp:12: warning: ‘b’ may be used uninitialized in this function user.cpp:12: warning: ‘d’ may be used uninitialized in this function