I want to find an index of a string only for first three char from an array
I have an array of month
string[] arrayEnglishMonth = { "JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY", "JUNE", "JULY", "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER" };
If I write
int t_ciMonth=8;(AUGUST)
int pos = Array.IndexOf(t_caMonth, arrayEnglishMonth[t_ciMonth - 1]);
But if I want the Index for only first 3 character i.e AUG how to find it?
arrayEnglishMonth.ToList().FindIndex(s => s.Substring(0,3) == "AUG");
arrayEnglishMonth, but in the t_caMonth array?
You have two options I can think of:
Linq only aproach that looks like this:
var index = arrayEnglishMonth.Select((v, i) => new { v, i })
.Where(c => c.v.StartsWith("AUG"))
.Select(c => c.i)
.First();
This will first iterate over existing array, create enumerable of anonymous objects holding values and indexes, where predicate passed in Where returns true, after that select only index and take the first element from enumerable.
Find respective month using Linq and then use IndexOf method:
var item = arrayEnglishMonth.First(c => c.StartsWith("AUG"));
var index = Array.IndexOf(arrayEnglishMonth, item);
t_caMonth in your answer? Take a more attentive look to the code in the question.
arrayEnlishMonth. Once s/he has index it's not a big deal to check if that index exists in another array.
WhereSelectEnumerableIterator will be used for iteration over array. I'll update answer.You can do this with a little Linq:
string[] arrayEnglishMonth = { "JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY", "JUNE", "JULY", "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER" };
string[] t_caMonth = { ... };
string search = arrayEnglishMonth[7].Substring(0, 3); // "AUG";
int pos = t_caMonth
.Select((s, i) => new { s, i }).Dump()
.Where(x => x.s == search)
.Select(x => x.i)
.DefaultIfEmpty(-1).First();
Or more simply:
int pos = t_caMonth.TakeWhile(s => s != search).Count();
Although this last solution will return t_caMonth.Length instead of -1 if no matching element is found.
Count in the second example doesn't do what you think it does. TakeWhile(...).Count() iterates through the list on til it finds an element that doesn't meet the condition (in this case, until it finds an a string that equals search) and then returns the number of items it had to go through until it found one--i.e. the index of the first match.This is mine way to achieve this
string[] arrayEnglishMonth = { "JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY", "JUNE", "JULY", "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER" };
var searcheditem = arrayEnglishMonth.FirstOrDefault(item => item.Substring(0, 3) == "AUG");
if(searcheditem != null)
var itemIndex = Array.IndexOf(arrayEnglishMonth, searcheditem);
but @wdavo answer is better
If the t_caMonth has upper casing and it's values have only 3 letters, you may use:
int pos = Array.IndexOf(t_caMonth, arrayEnglishMonth[t_ciMonth - 1]
.Substring(0,3));
In order to manage casing and values with more than 3 characters, you could have:
var pos = -1;
var sel = t_caMonth
.Select((i, index) => new { index, i = i.ToUpper() })
.Where(i =>
i.i.Substring(0,3) == arrayEnglishMonth[t_ciMonth - 1].Substring(0, 3))
.Select(i => i.index);
if (sel.Count() > 0)
pos = sel.FirstOrDefault();
You may also create a List<string> from your t_caMonth array:
var pos2 = t_caMonth
.ToList()
.FindIndex(i =>
i.ToUpper().Substring(0, 3) ==
arrayEnglishMonth[t_ciMonth - 1].Substring(0, 3));
Try using the following, i think it is the fastest
Array.FindIndex(strArray, s => s.StartsWith("AUG"));
Cheers.
t_caMonth?