Compilare: user.cpp: In function ‘int main()’: user.cpp:43:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(c) ; ^ In file included from /usr/include/c++/5/cstdio:42:0, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^ user.cpp:43:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(c) ; ^ In file included from /usr/include/c++/5/cstdio:42:0, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^ user.cpp:43:11: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(c) ; ^ In file included from /usr/include/c++/5/cstdio:42:0, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^ user.cpp:41:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("grad.in","r",stdin) ; ^ user.cpp:42:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("grad.out","w",stdout) ; ^ user.cpp:43:13: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(c) ; ^ user.cpp: In function ‘void grad(char*)’: user.cpp:22:43: warning: iteration 10u invokes undefined behavior [-Waggressive-loop-optimizations] for (j = 0 ; j <= 10 ; ++ j) f[j] = 0 ; ^ user.cpp:22:20: note: containing loop for (j = 0 ; j <= 10 ; ++ j) f[j] = 0 ; ^ /tmp/ccOTwwpS.o: In function `main': user.cpp:(.text.startup+0x38): warning: the `gets' function is dangerous and should not be used.