Compilare: main.cpp: In function 'int main()': main.cpp:71:16: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] s[n - 1] = NULL; ^~~~ main.cpp:62:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("strdup.in", "r", stdin); ^ main.cpp:63:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("strdup.out", "w", stdout); ^ main.cpp:66:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &t); ^ main.cpp:69:26: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(s, 1005, stdin); ^