Compilare: user.cpp: In function ‘int main()’: user.cpp:12:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(s + 1); ^ In file included from /usr/include/c++/5/cstdio:42:0, from /usr/include/x86_64-linux-gnu/c++/5/32/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:12:5: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(s + 1); ^ In file included from /usr/include/c++/5/cstdio:42:0, from /usr/include/x86_64-linux-gnu/c++/5/32/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:12:15: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] gets(s + 1); ^ In file included from /usr/include/c++/5/cstdio:42:0, from /usr/include/x86_64-linux-gnu/c++/5/32/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:24:44: warning: variable ‘last’ set but not used [-Wunused-but-set-variable] int left = 1 , right = j ,mid, last = -1; ^ user.cpp:8:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("blis.in", "r", stdin); ^ user.cpp:9:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("blis.out", "w", stdout); ^ user.cpp:11:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &k); ^ user.cpp:12:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s + 1); ^ /tmp/ccZ3VbDS.o: In function `main': user.cpp:(.text.startup+0x64): warning: the `gets' function is dangerous and should not be used.