Compilare: user.cpp: In function ‘int main()’: user.cpp:83:44: warning: NULL used in arithmetic [-Wpointer-arith] while(ln[k] != ' ' && ln[k] != NULL) { ^ user.cpp:69:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mexc.in", "r", stdin); ^ user.cpp:70:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mexc.out", "w", stdout); ^ user.cpp:75:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d\n", &n, &m, &d); ^ user.cpp:79:17: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(ln); ^ /tmp/cc1Ioxuw.o: In function `main': user.cpp:(.text.startup+0xaa): warning: the `gets' function is dangerous and should not be used.