Compilare: user.cpp: In function ‘bool find_num(unsigned int)’: user.cpp:30:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(*it==x) ^ user.cpp: In function ‘int main()’: user.cpp:45:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=nsec;i++) ^ user.cpp:51:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=nsec;i++) ^ user.cpp:57:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=nsec;i++) ^ user.cpp:37:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.in","r",stdin); ^ user.cpp:38:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.out","w",stdout); ^ user.cpp:40:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sir+1); ^ user.cpp:42:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(pattern+1); ^ /tmp/ccvhRjxt.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.