Set the digits after decimal point

I have a float number for example 12.12123 Is there a function which would display only number with 2 digits after decimal point 12.12 ?

Here is the code:

y1 = ( c1 - (a1 * x)) / b1;
 y2 = ( c2 - a2 * x) / b2;

if (y1 == y2)
  cout << "The same";

so if the y1 = 1.001 and the y2 = 1.002 they do not appear as the same.

I tried to add. cout.setf(ios::fixed, ios::floatfield); cout.precision(2);

but it does not seem to help.