View Compilation Error

0_0_20072481_31033.cpp: In function 'int main()':
0_0_20072481_31033.cpp:5:46: error: 'scanf' was not declared in this scope
  while(scanf("%lf%lf%lf%lf\n",&x1,&y1,&x2,&y2)!=EOF)
                                              ^
0_0_20072481_31033.cpp:5:49: error: 'EOF' was not declared in this scope
  while(scanf("%lf%lf%lf%lf\n",&x1,&y1,&x2,&y2)!=EOF)
                                                 ^
0_0_20072481_31033.cpp:8:14: error: 'sqrt' was not declared in this scope
      s=sqrt(q);
              ^
0_0_20072481_31033.cpp:9:32: error: 'printf' was not declared in this scope
      printf("%0.2f %0.2f\n",q,s);
                                ^