Compilare: user.cpp: In function ‘int main()’: user.cpp:6: warning: unused variable ‘i’ user.cpp:6: warning: unused variable ‘j’ user.cpp:6: warning: unused variable ‘cate’ user.cpp:11: warning: unused variable ‘p’ user.cpp:4: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:5: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:8: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:9: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result /tmp/ccygOr4X.o: In function `main': user.cpp:(.text+0x8a): warning: the `gets' function is dangerous and should not be used.