Compilare: user.cpp: In function ‘void impartire(char*, char*, int, int)’: user.cpp:25:11: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] b[cif]=NULL; ^ user.cpp: In function ‘int main()’: user.cpp:34:11: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] a[n+m]=NULL; ^ user.cpp:39:16: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] a[la-1]=NULL; ^ user.cpp:46:12: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] a2[m+2]=NULL; ^ user.cpp:29:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numar4.in", "r", stdin); ^ user.cpp:30:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numar4.out", "w", stdout); ^ user.cpp:31:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d ", &n,&m); ^ user.cpp:33:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c ", &a[i]); ^