It is often being claimed that D is at least as fast as C++.
Now, I am fairly new to D. But, here is an example where I want to see how can this be made possible.


So far my C++ code compiles in ~850 ms.
While my D code runs in about 2.1 seconds.

The code translated in D looks as follows (can't see any attach button here):

import std.stdio, std.math;
import std.datetime;


int main() {

        StopWatch sw;
        sw.start();

        double C=0.0;

        for (int k=0;k<10000;++k) { // iterate 1000x

                double S0 = 100.0;
                double r = 0.03;
                double alpha = 0.07;
                double sigma = 0.2;
                double T = 1.0;
                double strike = 100.0;
                double S = 0.0;


                const int n = 252;

                double dt = T / n;
                double R = exp(r*dt);

                double u = exp(alpha*dt + sigma*sqrt(dt));
                double d = exp(alpha*dt - sigma*sqrt(dt));

                double qU = (R - d) / (R*(u - d));
                double qD = (1 - R*qU) / R;


                //double* call = new double [n + 1];
                double[] call = new double[n+1];

for (int i = 0; i <= n; ++i) call[i] = fmax(S0*pow(u, n-i)*pow(d, i)-strike, 0.0);
                
                for (int i = n-1; i >= 0 ; --i) {
                        for (int j = 0; j <= i; ++j) {
                                call[j] = qU * call[j] + qD * call[j+1];
                        }
                }

                C = call[0];

//delete call; // since D is has a garbage collector, explicit deallocation of arrays is not necessary.
            // nevertheless we do this
        }

    long exec_ms = sw.peek().msecs;

writeln("Option value: ", C, " / execution time: ", exec_ms, " ms\n" );

        return 0;
}

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