While searching for an answer to this question, I've run into similar ones utilizing LINQ but I haven't been able to fully understand them (and thus, implement them), as I'm not familiarized with it. What I would like to, basically, is this:
- Check if any element of a list contains a specific string.
- If it does, get that element.
I honestly don't know how I would go about doing that. What I can come up with is this (not working, of course):
if (myList.Contains(myString)) string element = myList.ElementAt(myList.IndexOf(myString));I know WHY it does not work:
myList.Contains()does not returntrue, since it will check for if a whole element of the list matches the string I specified.myList.IndexOf()will not find an occurrence, since, as it is the case again, it will check for an element matching the string.
Still, I have no clue how to solve this problem, but I figure I'll have to use LINQ as suggested in similar questions to mine. That being said, if that's the case here, I'd like for the answerer to explain to me the use of LINQ in their example (as I said, I haven't bothered with it in my time with C#). Thank you in advance guys (and gals?).
EDIT: I have come up with a solution; just loop through the list, check if current element contains the string and then set a string equal to the current element. I'm wondering, though, is there a more efficient way than this?
string myString = "bla";
string element = "";
for (int i = 0; i < myList.Count; i++)
{ if (myList[i].Contains(myString)) element = myList[i];
}13 Answers
You should be able to use Linq here:
var matchingvalues = myList .Where(stringToCheck => stringToCheck.Contains(myString));If you simply wish to return the first matching item:
var match = myList .FirstOrDefault(stringToCheck => stringToCheck.Contains(myString));
if(match != null) //Do stuffThe basic answer is: you need to iterate through loop and check any element contains the specified string. So, let's say the code is:
foreach(string item in myList)
{ if(item.Contains(myString)) return item;
}The equivalent, but terse, code is:
mylist.Where(x => x.Contains(myString)).FirstOrDefault();Here, x is a parameter that acts like "item" in the above code.
1string result = myList.FirstOrDefault(x => x == myString)
if(result != null)
{ //found
}for (int i = 0; i < myList.Length; i++)
{ if (myList[i].Contains(myString)) // (you use the word "contains". either equals or indexof might be appropriate) { return i; }
}Old fashion loops are almost always the fastest.
4If you want a list of strings containing your string:
var newList = myList.Where(x => x.Contains(myString)).ToList();Another option is to use Linq FirstOrDefault
var element = myList.Where(x => x.Contains(myString)).FirstOrDefault();Keep in mind that Contains method is case sensitive.
You could use Linq's FirstOrDefault extension method:
string element = myList.FirstOrDefault(s => s.Contains(myString));This will return the fist element that contains the substring myString, or null if no such element is found.
If all you need is the index, use the List<T> class's FindIndex method:
int index = myList.FindIndex(s => s.Contains(myString));This will return the the index of fist element that contains the substring myString, or -1 if no such element is found.
Many good answers here, but I use a simple one using Exists, as below:
foreach (var setting in FullList)
{ if(cleanList.Exists(x => x.ProcedureName == setting.ProcedureName)) setting.IsActive = true; // do you business logic here else setting.IsActive = false; updateList.Add(setting);
}You should be able to use something like this, it has worked okay for me:
var valuesToMatch = yourList.Where(stringCheck => stringCheck.Contains(myString));or something like this, if you need to look where it doesn't match.
var valuesToMatch = yourList.Where(stringCheck => !stringCheck.Contains(myString));you can use
var match=myList.Where(item=>item.Contains("Required String"));
foreach(var i in match)
{
//do something with the matched items
}LINQ provides you with capabilities to "query" any collection of data. You can use syntax like a database query (select, where, etc) on a collection (here the collection (list) of strings).
so you are doing like "get me items from the list Where it satisfies a given condition"
inside the Where you are using a "lambda expression"
to tell briefly lambda expression is something like (input parameter => return value)
so for a parameter "item", it returns "item.Contains("required string")" . So it returns true if the item contains the string and thereby it gets selected from the list since it satisfied the condition.
To keep it simple use this;
foreach(string item in myList)//Iterate through each item.
{ if(item.Contains("Search Term")//True if the item contains search pattern. { return item;//Return the matched item. }
}Alternatively,to do this with for loop,use this;
for (int iterator = 0; iterator < myList.Count; iterator++) { if (myList[iterator].Contains("String Pattern")) { return myList[iterator]; } }It is possible to combine Any, Where, First and FirstOrDefault; or just place the predicate in any of those methods depending on what is needed.
You should probably avoid using First unless you want to have an exception thrown when no match is found. FirstOrDefault is usually the better option as long as you know it will return the type's default if no match is found (string's default is null, int is 0, bool is false, etc).
using System.Collections.Generic;
using System.Linq;
bool exists;
string firstMatch;
IEnumerable<string> matchingList;
var myList = new List<string>() { "foo", "bar", "foobar" };
exists = myList.Any(x => x.Contains("o"));
// exists => true
firstMatch = myList.FirstOrDefault(x => x.Contains("o"));
firstMatch = myList.First(x => x.Contains("o"));
// firstMatch => "foo"
firstMatch = myList.First(x => x.Contains("dark side"));
// throws exception because no element contains "dark side"
firstMatch = myList.FirstOrDefault(x => x.Contains("dark side"));
// firstMatch => null
matchingList = myList.Where(x => x.Contains("o"));
// matchingList => { "foo", "foobar" }Test this code @
I have not seen bool option in other answers so I hope below code will help someone.
Just use Any()
string myString = "test";
bool exists = myList .Where(w => w.COLUMN_TO_CHECK.Contains(myString)).Any();You can check the list is empty or not in multiple ways.
1)Check list is null and then check count is greater than zero like below:-
if(myList!=null && myList.Count>0)
{ //List has more than one record.
}2)Check list null and count greater than zero using linq query like below:-
if(myList!=null && myList.Count>0)
{ //List has more than one record.
}
