The **setprecision() function** is a built-in function that comes with the `iomanip` library. As the name suggests, it helps us to set the precision (significant figures/decimal​ places) of an output.

# Significant figures
The function takes in *one* argument: the number of significant figures required in the ​output.

#include <iostream>
#include <iomanip>

using namespace std;
int main() {

  float pi = 3.141592;
  cout << setprecision(4) << pi;

}

# Decimal places
To manipulate the decimal places being displayed in the output, add a `fixed` keyword before the `setprecision()` function (as shown below). The function will still take in only ​one argument, but it will be the number of decimal places required in the output. 

#include <iostream>
#include <iomanip>

using namespace std;
int main() {

  float pi = 3.141592;
  cout << fixed << setprecision(4) << pi;

}

What is the setprecision function in C++?

Significant figures

Decimal places