how print fload wiht 3 decimal in c 2b 2b

1#include <iostream>
2#include <iomanip>
3
4int main()
5{
6    double d = 122.345;
7
8    std::cout << std::fixed;
9    std::cout << std::setprecision(2);
10    std::cout << d;
11}

1#include <iostream>
2#include <iomanip>
3
4int main()
5{
6    double d = 122.345;
7    std::cout << std::fixed << std::setprecision(2) << d;
8}
9
10//result that get print out: 122.34

1#include <iostream>
2#include <cstdio>
3using namespace std;
4
5int main() 
6{
7    // This code helps you to print a number with desired decimal
8    double Number=10.3454;
9    printf("%.3lf",Number);
10
11    return 0;
12}

1std::cout << std::setprecision(2) << std::fixed;
2// where the 2 is how many decimal places you want
3// note you need to <iomanip>