2023.8.11 周五：保留小数点后几位

 1 #include <iostream>
 2 #include <iomanip>
 3 int main()
 4 {
 5     int n;
 6     cin >> n;
 7     double PI = 3.14159265358979;
 8     cout << setprecision(n) << fixed << PI << endl;
 9     return 0;
10 }

1 #include <stdio.h>
2 int main()
3 {
4     double PI = 3.14159265358979;
5     printf("%.4f\n",PI);
6     return 0;
7 }

1 //java
2 System.out.println(String.format("%.2f",num));