Is there a way to repeat the code, with different variables without having to repeat the code by han-CodePudding

I am trying to use C# to do math, and in this case I need to repeat a string of code multiple times and then sum the results, the only thing that changes is one number that goes from 2 to 10. (I am aware python might be a better language to do math)

A thought that I had was doing a while loop, but I don't know how to use the while loop to do what I want.

static void Main()
{
    double r = 5;
    double n = 12;
    double fact = 1;
    double foct = 1;
    double fuct = 1;
    double p = 0.85;
    {
        for (double x = 1; x <= n; x  )
        {
            fact *= x;
        }
        for (double y = 1; y <= r; y  )
        {
            foct *= y;
        }
        for (double z = 1; z <= n - r; z  )
        {
            fuct *= z;
        }
    }
    Console.WriteLine((fact / (foct * fuct) * Math.Pow(p, r) * Math.Pow(1 - p, n - r)));
}

More specifically, I need to make the r go from 2 to 10, and then sum up each result after, which I could do by just repeating the code and summing everything up, but I wonder if there is a way of automating it.

I am new to coding as you may be able to tell, so things might not be so obvious to me.

CodePudding user response：

Perhaps wrapping your function in a for loop would work. You could then use the index of the loop to set your r value:

for (int i = 2; i < 11; i  )
{
    double r = i;
    double n = 12;
    double fact = 1;
    double foct = 1;
    double fuct = 1;
    double p = 0.85;

    for (double x = 1; x <= n; x  )
    {
        fact *= x;
    }
    for (double y = 1; y <= r; y  )
    {
        foct *= y;
    }
    for (double z = 1; z <= n - r; z  )
    {
        fuct *= z;
    }

    Console.WriteLine((fact / (foct * fuct) * Math.Pow(p, r) * Math.Pow(1 - p, n - r)));
}

If you wanted to use those values inside of the for loop to create a sum, you would then need to employ the same tactics you were using with your other for loops -- declare the variables outside of the loop:

double sum = 0;

for (int i = 2; i < 11; i  )
{
    double r = i;
    double n = 12;
    double fact = 1;
    double foct = 1;
    double fuct = 1;
    double p = 0.85;

    for (double x = 1; x <= n; x  )
    {
        fact *= x;
    }
    for (double y = 1; y <= r; y  )
    {
        foct *= y;
    }
    for (double z = 1; z <= n - r; z  )
    {
        fuct *= z;
    }

    // capture the value here to add to sum, we can also print that value then
    double value = (fact / (foct * fuct) * Math.Pow(p, r) * Math.Pow(1 - p, n - r));
    sum  = value;
    Console.WriteLine(value);
}

Console.WriteLine("Sum: "   sum);

CodePudding user response：

You could make it way shorter by using enumerable and linq I think. By example you could replace the first loop (for the factorial) with :

var fact = Enumerable.Range(1, 12).Aggregate(1, (accumulator, nextValue) => accumulator * nextValue);

Small explanation :

Enumerable.Range(1, 12)

Will create an enumerable containing value from 1 to 12.

.Aggregate(1, (accumulator, nextValue) => accumulator * nextValue);

Will aggregate all values in your enumerable into a single one. The initial value (the seed) will be 1 and for each value in the enumerable the aggregation function will apply (current value (aka accumulator) * next value in the enumerable).

Once you understand the full line you can simply reuse it with different values of course.

Then you can create a method for it to reuse easily :

public static int Factorial(int value)
{
    return Enumerable.Range(1, value).Aggregate(1, (accumulator, nextValue) => accumulator * nextValue);
}