Compilare: user.cpp: In function ‘int main()’: user.cpp:15:10: warning: unused variable ‘out’ [-Wunused-variable] FILE *out = fopen("gcycle.out", "w"); ^ user.cpp:17:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d %d", &N, &M); ^ user.cpp:23:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &i, &j); ^