How to use loop for ?

Question

1.00/5 (1 vote)

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i have example;

C#

 if (a == "8")
    comboBox3.SelectedIndex = 0;

if (a == "9")
    comboBox3.SelectedIndex = 1;
if (a == "10")
    comboBox3.SelectedIndex = 2;

if (a == "11")
    comboBox3.SelectedIndex = 3;
if (a == "12")

What I have tried:

I want to use loop for, make this code short, everyone can help me, thanks

Posted 17-Mar-16 4:42am

Hoang Thang Vo

Updated 17-Mar-16 20:15pm

Patrice T

v2

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Peter Leow 17-Mar-16 10:49am

comboBox3.SelectedIndex = Int32.Parse(a) - 8;

CHill60 17-Mar-16 10:54am

Good solution!

Hoang Thang Vo 17-Mar-16 12:36pm

I mean not that,i think how to not rewrite many sentences if

ZurdoDev 17-Mar-16 10:54am

If it is as simple as you have shown, then Peter has given you a one line solution. However, do you need a loop and where are you stuck?

Hoang Thang Vo 17-Mar-16 12:25pm

I think I need one loop eliminates the need to rewrite much if statement

ZurdoDev 17-Mar-16 12:43pm

Where are you stuck then?

CHill60 17-Mar-16 10:56am

I can't see any reason why you would need a loop in this scenario.
Perhaps you were thinking of switch? switch (C# Reference)[^]

Hoang Thang Vo 17-Mar-16 12:26pm

I'm looking to not rewrite many sentences if

CHill60 17-Mar-16 13:10pm

You wouldn't write any if-statements if you used switch

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Sascha Lefèvre · Accepted Answer · 2016-03-17T04:59:00

First of all: Don't use Magic numbers - Wikipedia[^]

A for loop won't help. What you have there is a mapping: You map "8" to 0, "9" to 1 etc. And a map in C# is a dictionary. I'm not sure what you're trying to do there couldn't be done in a completely different and better way but with a dictionary it would look like this:

C#

// create the dictionary at some central place so that it
// only needs to be created once:
Dictionary<string, int> SelectedIndexMapping = new Dictionary<string, int>()
{
   { "8", 0 },
   { "9", 1 },
   // etc
};


// and then somewhere else instead of your shown code:
comboBox3.SelectedIndex = SelectedIndexMapping[a];

// or, if the string a could contain an invalid value:
int index;
if (SelectedIndexMapping.TryGetValue(a, out index))
   comboBox3.SelectedIndex = index;
else
   // show an error-message or set comboBox3.SelectedIndex to some default value

Also, just occurred to me, if the index is always smaller by 8 than the number in a then instead of the dictionary you could parse the value in a into an integer, subtract 8 and assign the result to comboBox3.SelectedIndex:

C#

int index;
if (Int32.TryParse(a, out index))
    comboBox3.SelectedIndex = index - 8;
else
    // show an error-message or set comboBox3.SelectedIndex to some default

Edit: fixed a brain fart with TryParse(..) in the second code example