Compilare: user.cpp: In function ‘int main()’: user.cpp:29:14: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] for(i=1; gets(mat[i])!=NULL; i++); ^~~~ In file included from /usr/include/c++/6/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:29:25: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations] for(i=1; gets(mat[i])!=NULL; i++); ^ In file included from /usr/include/c++/6/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:26:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] { freopen("randuri.in", "r",stdin); ^ user.cpp:27:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("randuri.out", "w",stdout); ^ /tmp/cc7OGUSY.o: In function `main': user.cpp:(.text.startup+0x5b): warning: the `gets' function is dangerous and should not be used.