How can I convert a float 2.3 to 2.300

Question

or 1.54632 to 1.546

Answer 1

Use header file iomanip. And use function setprecision. Like this:
#include<iostream>
#include<iomanip>
using namespace std;

int main()
{
float a=2.3;
float b=1.523469;
cout<<fixed;
cout<<setprecision(4)<<a<<endl;
cout<<setprecision (3)<<b<<endl;

return 0;
}