Compilare: user.cpp: In function ‘int main()’: user.cpp:173:28: warning: NULL used in arithmetic [-Wpointer-arith] for (int j=0;s[j]!=NULL;j++) ^ user.cpp:230:28: warning: NULL used in arithmetic [-Wpointer-arith] for (int j=2;s[j]!=NULL;j++) ^ user.cpp:162:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("disconnect.in","r",stdin); ^ user.cpp:163:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("disconnect.out","w",stdout); ^ user.cpp:165:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&n,&m); ^ user.cpp:168:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ user.cpp:224:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccIdQhPX.o: In function `main': user.cpp:(.text.startup+0x88): warning: the `gets' function is dangerous and should not be used.