Compilare: user.cpp: In function ‘void f(char*)’: user.cpp:40: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:54: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:55: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:56: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:57: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp:61: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result /tmp/ccQcXoKp.o: In function `main': user.cpp:(.text+0x3ca): warning: the `gets' function is dangerous and should not be used.