Compilare: user.cpp: In function ‘int main()’: user.cpp:32:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(s); ^~~~ In file included from /usr/include/c++/6/cstdio:42:0, from /usr/include/x86_64-linux-gnu/c++/6/32/bits/stdc++.h:46, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^~~~ user.cpp:32:11: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(s); ^ In file included from /usr/include/c++/6/cstdio:42:0, from /usr/include/x86_64-linux-gnu/c++/6/32/bits/stdc++.h:46, from user.cpp:1: /usr/include/stdio.h:638:14: note: declared here extern char *gets (char *__s) __wur __attribute_deprecated__; ^~~~ user.cpp:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < strlen(s); i++) ~~^~~~~~~~~~~ user.cpp:29:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("spion.in","r",stdin); ^ user.cpp:30:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("spion.out","w",stdout); ^ user.cpp:31:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&p); ^ user.cpp:32:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/cchVy8px.o: In function `main': user.cpp:(.text.startup+0x57): warning: the `gets' function is dangerous and should not be used.