How to Set Precision in C++

Programmers who use C++ for problem solving may need to set precision before printing floating numbers in standard output.

To display a floating number value of variable result with precision 2 (equivalent to .%2lf in scanf) use following code:

1 cout.setf (ios::fixed, ios::floatfield); 2 cout.setf(ios::showpoint); 3 cout<<setprecision(2)<<result<<endl;

Here’s an example code used to solve a problem in easy volume section.

1 /******************************************************* 2 * Problem Name: Money in the bag 3 * Problem ID: 1002 4 * Occassion: Offline Contest CSEDU Easy Volume 5 * 6 * Algorithm: 7 * Special Case: 8 * Judge Status: Accepted 9 * Author: Saint Atique 10 * Notes: 11 * 12 *******************************************************/ 13 14 #define _CRT_SECURE_NO_DEPRECATE 1 15 //#define _CRT_NONSTDC_NO_DEPRECATE 16 17 #include <iostream> 18 #include <cmath> 19 #include <cstring> 20 //#include <new> 21 #include <vector> 22 #include <queue> 23 #include <map> 24 #include <algorithm> 25 #include <iomanip>//for cout formatting 26 #define INF 2147483648 27 #define EPS 1e-8 28 using namespace std; 29 30 int main() { 31 //freopen("..\\1002_in.txt", "r", stdin); 32 //freopen("..\\1002_out.txt", "w", stdout); 33 34 double tk_amount[10] = {1000, 500, 100, 50, 20, 10, 5, 2, 1, 0.50}; 35 double sum = 0; 36 int i, n; 37 38 for (i=0; i<10; i++) { 39 cin>>n; 40 sum += n * tk_amount[i]; 41 } 42 43 cout.setf (ios::fixed, ios::floatfield); 44 cout.setf(ios::showpoint); 45 cout<<setprecision(2)<<sum<<" taka"<<endl; 46 47 //fclose(stdin); 48 //fclose(stdout); 49 return 0; 50 }