Compilare: user.cpp: In function ‘int main()’: user.cpp:35:16: warning: unused variable ‘b’ [-Wunused-variable] double b = fabs( (A*1.0)*(1.0*X) + (B*1.0)*(Y*1.0) - 1.0 ) / sqrt(A*A + B*B) ; ^ user.cpp:27:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("distanta.in", "r", stdin); ^ user.cpp:28:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("distanta.out", "w", stdout); ^ user.cpp:30:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &tests); ^ user.cpp:33:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &A, &B, &X, &Y); ^