How to use setprecision in cpp for only the number of floating points

Question

When cout-ing a number with floating points, i.e. 31.14159, how can I set cout to use the setprecision(4) on the floating point:

cout <<setprecision(4)<< 31.14159<<endl; // returns 31.14

As-is, it considers the whole number with its decimal digits, and outputs: 31.14. However, I want to get: 31.1416.

Answer 1

std::fixed says that there will be a fixed number of decimal digits after the decimal point.

std::cout << std::setprecision(4) << std::fixed << 31.14159;

- this will print 31.1416

Answer 2

You can use std::fixed

std::cout << std::fixed << std::setprecision(4) << 31.14159 << endl ;

and you will get output as 31.1416

When you add std::fixed, the std::setprecision(4) will take effect on the decimal part, and thus you will get 4 values after the decimal point.

A std::setprecision() will take effect on the entire number. But when you add a std::fixed along with it, the std::setprecision() will effect only the decimal part of the number.