View Compilation Error

0_0_31674509_25669.cpp: In function 'int main()':
0_0_31674509_25669.cpp:4:2: error: 'string' was not declared in this scope
  string s;
  ^
0_0_31674509_25669.cpp:6:26: error: 's' was not declared in this scope
  while(scanf("%s%lf%lf",&s ,&a, &b)!=EOF){
                          ^