What is the precision of floating point in C++?

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In C++, the size of the floating point number is either 4-byte or 8-bytes. So it can store up to few decimal places. For example, the 1/3 = 0.333333…… Up to infinity. If we store it inside floating type variable, then it will store some significant digits. The default value is 6. So normally floating point numbers in C++ can display up to 6 decimal places.

We can change the size of the precision using setprecision. This is present inside the iomanip header file. Let us see one example to get the idea.

Example Code

#include <iostream>
#include <iomanip>
using namespace std;
int main() {
double x = 2.3654789d;
cout << "Print up to 3 decimal places: " << setprecision(3) << x << endl;
cout << "Print up to 2 decimal places: " << setprecision(2) << x << endl;
cout << "Print up to 7 decimal places: " << setprecision(7) << x << endl;
}

Output

Print up to 3 decimal places: 2.365
Print up to 2 decimal places: 2.37
Print up to 7 decimal places: 2.3654789
Published on 28-May-2019 12:29:19