1. Formatting the Output
The C++ standard library supplies many manipulators:
endl, setw, fixed, showpoint, setprecesion.
If we want to use endl, fixed, or showpoint, we need to include
the header file iostream.
#include <iostream>
If we want to use setw or setprecision, we need to include
the header file iomanip.
#include <iomanip>

2. The manipulator setw Setw means set width.
The argument of setw is an integer. This integer gives the field width.
The output is right-justified.
Example:
int ans = 33;
int num = 7132; Output
cout << setw(4) << ans  33 7132  Hi
<< setw(5) << num
<< set(4) <, “Hi”;
Cout << setw(1) << ans 7132
<< setw(5) << num; 4 5 4 5
Field width will expand to fit the 2-digit value

3. The manipulator setprecision
Value of x Statement Output
cout << setw(10)
<< setprecision(2) << x;    310.00
<< setprecision(5) << x; 
cout << setw(7)
<< setprecision(5) << x;
(expands width to 9)
cout << setw(6)
<< setprecision(2) << x;  4.83
(last displayed digit is
round off)

4. Manipulators fixed and showpoint
You can use manipulator named fixed to force all subsequent
floating point output to appear in decimal form rather than
scientific notation:
cout << fixed << 3.8 * x;
To force decimal points to be displayed in subsequent floating-point
output, even for whole numbers, you can use the manipulator
showpoint:
cout << showpoint << floatVar;