View Compilation Error

0_0_13985131_30869.cpp: In function 'int main()':
0_0_13985131_30869.cpp:4:50: error: 'scanf' was not declared in this scope
     while(scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2)!=EOF)  
                                                  ^
0_0_13985131_30869.cpp:4:53: error: 'EOF' was not declared in this scope
     while(scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2)!=EOF)  
                                                     ^
0_0_13985131_30869.cpp:6:54: error: 'sqrt' was not declared in this scope
         result = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));  
                                                      ^
0_0_13985131_30869.cpp:7:32: error: 'printf' was not declared in this scope
         printf("%.2lf/n",result);          
                                ^