View Compilation Error

0_0_19943864_456.cpp: In function 'int main()':
0_0_19943864_456.cpp:5:22: error: 'scanf' was not declared in this scope
  while(scanf("%lf",&r)!=EOF)
                      ^
0_0_19943864_456.cpp:5:25: error: 'EOF' was not declared in this scope
  while(scanf("%lf",&r)!=EOF)
                         ^
0_0_19943864_456.cpp:8:21: error: 'printf' was not declared in this scope
   printf("%.3lf\n",v); 
                     ^