Compilare: user.cpp: In function ‘bool ok_lower(int, int)’: user.cpp:35:13: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] aux[l2] = NULL; ^ user.cpp: In function ‘bool ok_upper(int, int)’: user.cpp:50:13: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] aux[l2] = NULL; ^ user.cpp: In function ‘int main()’: user.cpp:66:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d\n", &n); ^ user.cpp:69:34: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(s+i*F+1, 1, F, fin); ^ user.cpp:70:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%c", &aux); ^ user.cpp:96:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &m); ^ user.cpp:103:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%s", c); ^