Compilare: user.cpp: In function ‘void readdata()’: user.cpp:8: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:9: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:11: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:27: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result In file included from /usr/include/stdio.h:910, from /usr/include/c++/4.4/cstdio:45, from user.cpp:1: In function ‘char* gets(char*)’, inlined from ‘void readdata()’ at user.cpp:11: /usr/include/bits/stdio2.h:230: warning: call to ‘__gets_warn’ declared with attribute warning: please use fgets or getline instead, gets can't specify buffer size user.cpp: In function ‘int main()’: user.cpp:26: warning: ‘aux’ may be used uninitialized in this function /tmp/cc8MfEsV.o: In function `readdata()': user.cpp:(.text+0x142): warning: the `gets' function is dangerous and should not be used.