Compilare: user.cpp: In function ‘int main()’: user.cpp:29:34: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] nr[k]=NULL; ^ user.cpp:39:34: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] nr[k]=NULL; ^ user.cpp:48:38: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] nr[k]=NULL; ^ user.cpp:57:42: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] nr[k]=NULL; ^ user.cpp:7:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ecuatii2.in", "r", stdin); ^ user.cpp:8:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ecuatii2.out", "w", stdout); ^ user.cpp:11:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &n); ^ user.cpp:14:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccWXvUY9.o: In function `main': user.cpp:(.text.startup+0x83): warning: the `gets' function is dangerous and should not be used.