Calling a function dynamically based on an integer value

Question

I want to call a different function without write if conditions like this:

if(a==1)
{
    function1 ();
}
if(a==2)
{
    function2 ();
}
if(a==3)
{
    function3 ();
}

I want to call function like this :

Dictionary<int, function> functions= new Dictionary<int, function>();
functions.add(1, function1);functions.add(2, function2);functions.add(3, function3);

function[1];

How can I do this?

Have you heard about delegates ? Change your function what says @Sinatr and invoke like this function[1]() — Suren Srapyan
– Suren Srapyan, Commented Nov 23, 2015 at 13:04
Also read about delegates before you read about Func<> and Action<>, — Lior Dadon
– Lior Dadon, Commented Nov 23, 2015 at 13:08

M.kazem Akhgary · Accepted Answer · 2015-11-23 13:41:12Z

3

It seems your functions are actually actions, since a function returns a value. Also you don't have any method parameters, so you have to use Action.

Dictionary<int, Action> functions= new Dictionary<int, Action>();
functions.Add(1, function1);
functions.Add(2, function2);
functions.Add(3, function3);

function[1](); // <-- calling here needs parentheses

edited Nov 23, 2015 at 13:41

M.kazem Akhgary

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answered Nov 23, 2015 at 13:07

Patrick Hofman

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2 Comments

Patrick Hofman Over a year ago

No, unless you wrap that call in an action too (if possible). It is all the same or not.

mister Over a year ago

there is no another issue??

Dbuggy · Accepted Answer · 2015-11-23 13:08:13Z

1

You can do something like the following

void Main()
{
    Dictionary<int, Func<bool>> funcMap = new Dictionary<int, Func<bool>>() {
        {1, Function1},
        {2, Function2}
    };


    Console.WriteLine(funcMap[1]());
    Console.WriteLine(funcMap[2]());
}

// Define other methods and classes here


bool Function1()
{
    return true;
}

bool Function2()
{
    return false;
}

This works because all functions have the same signature.

answered Nov 23, 2015 at 13:08

Dbuggy

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2 Comments

mister Over a year ago

thank you for the answer. but I can I have it with different signature

Dbuggy Over a year ago

Possibly you need to explain how your code is getting used. You didn't gave us much to work with.

Sinatr · Accepted Answer · 2015-11-23 13:46:06Z

1

You can use lambdas to map functions with different signatures. Idea is the same as with Action:

var functions = new Dictionary<int, Action>
{
    { 1, () => method1(123) },
    { 2, () => method2(123, "123") },
};

functions[1](); // will call method1(123);

where functions are defined like this

void method1(int a) => Console.WriteLine(a);
void method2(int a, string b) => Console.WriteLine(a + b);

answered Nov 23, 2015 at 13:46

Sinatr

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