Pass += or -= as a parameter in c#

Question

I have a method from a button click with the following code in c# (small golf scoring program I'm working on just for fun):

private void btnPlus_Click(object sender, EventArgs e)
{
    btnMinus.Enabled = true;
    if (f_intHoleNumber != 18) { f_intHoleNumber += 1; }
    if (f_intHoleNumber == 18) { btnPlus.Enabled = false; }
    txtHoleNumber.Text = f_intHoleNumber.ToString();            
}

I would like to refactor that and extract another method from it so I don't reuse code but i'm not sure if its possible to pass an operator (+=) as a parameter to a method. Can this be done?

create two methods: First will increase your value, the second one - decrease. Whats a problem? — SᴇM, Mar 21 '16 at 13:25
Simpler yet, pass the value: `f_intHoleNumber += value`, where `value` is `+1/-1` . — xanatos, Mar 21 '16 at 13:26

score 5 · Accepted Answer · edited Mar 21 '16 at 13:43

5

I don't think so. What about passing +1 or -1 to the method and multiplying it with the value to add or to subtract. For example:

public float calc(float val1, float val2, int op) 
{
    return val1 + op * val2;
}

edited Mar 21 '16 at 13:43

daniel59

906
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answered Mar 21 '16 at 13:25

1

Or simply pas in `-1 * value`. – Patrick Hofman Mar 21 '16 at 13:27
Never even thought of that. Good deal. Thanks! – snapper Mar 21 '16 at 13:32
I'm glad I was able to help. :) – Mar 21 '16 at 15:13

score 0 · Answer 2 · edited May 23 '17 at 10:28

0

You can pass a method that does the adding and subtracting for you. You probably want to go that route. Pass Method as Parameter using C#

edited May 23 '17 at 10:28

Community

1
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answered Mar 21 '16 at 13:25

JP Hochbaum

637
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1

This is more a comment than an answer. – Patrick Hofman Mar 21 '16 at 13:27
Sorry, didn't realize there was a difference. – JP Hochbaum Mar 21 '16 at 13:28
You are not really providing a solution, just a link to a solution. [That is more of a comment.](http://meta.stackexchange.com/q/225370/245360) – Patrick Hofman Mar 21 '16 at 13:29

score 0 · Answer 3 · answered Mar 21 '16 at 13:37

You could pass a Func<int, int> which accepts one int parameter and returns an int.

private void btnPlus_Click(object sender, EventArgs e)
{
    HandleHoleChange(currentHole => currentHole + 1);      
}

private void HandleHoleChange(Func<int, int> getNextHoleFunc)
{
    btnMinus.Enabled = true;
    if (f_intHoleNumber != 18) { f_intHoleNumber = getNextHoleFunc(f_intHoldNumber); }
    if (f_intHoleNumber == 18) { btnPlus.Enabled = false; }
    txtHoleNumber.Text = f_intHoleNumber.ToString();         
}

score 0 · Answer 4 · answered Apr 29 '20 at 10:41

the accepted answer allows to pass a 0 which would mess up the calculation. If you want only to allow for addition or subtraction you can use a boolean variable to specify it in the parameterlist:

public float calc(float val1, float val2, bool add) 
{
    int op = add ? 1 : -1;
    return val1 + op * val2;
}

Pass += or -= as a parameter in c#

4 Answers4