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I want to convert ILIST<string> to ILIST <object>
How can achieve this using C#?
var oList = (IList<object>)sList.Cast<object>().ToList();
IList<string> s = new List<string>() ;
IList<object> o = new List<object>();
foreach (string x in o)
s.Add(x);
The following should do it:
IList<String> strings = new List<String> { "a", "b", };
IList<Object> objects = strings.Cast<Object>().ToList();
You can test the results in LinqPad by calling: objects.Dump();
stringList.Select(x => (object)x).ToList();
that is what the Lambda expressions are for.
you can use a simple Lambda expression for the conversion. Provided you are on .NET 2.0 or above.
eg:
stringList.Select(x => (object)x).ToList();
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I need to do a LINQ expression where the expression varies on how deep the expected node is in the hierarchy.
So I use concat on a string like this:
var parString = string.Concat(Enumerable.Repeat(".SelectMany(f => f.level)", level));
so if its 4 levels deep I get the string :
string1 = ".SelectMany(f => f.level).SelectMany(f => f.level).SelectMany(f => f.level).SelectMany(f => f.level)"
I then want to use this string in a LINQ expression, example:
List + string1 + .FirstOrDefault(.......);
Is this even possible? How can I do it?
Use a for loop to determine how many times to call .SelectMany:
var query = List;
for(int depth = 4; depth > 0; depth--)
{
query = query.SelectMany(f => f.level);
}
// Materialize query with `FirstOrDefault` or anything you need
Notice that currently if you reach the maximum depth and still continue you will get an exception. To solve that you can add an if statement to check that f.level is not null or not empty depending on your logic. Something like:
for(int depth = 4; depth > 0; depth--)
{
query = query.SelectMany(f => f.level ?? Enumerable.Empty<YourType>());
}
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I wanted to try some examples in C# using collections and generics but I am stuck at this example.
This is my code in c#,
public List<string> CurrentCount(int week, int year)
{
List<string> lst = new List<string>();
lst.Add("current:");
lst.Add("10");
lst.Add("target:");
lst.Add("15");
return lst;
}
It gives me result like this :
["current:","10","target:","15"]
But I want it like this :
["current": 10,"target": 15] or
["current": "10","target": "15"]
Any ideas will be helpful.
Thanks.
You want a Dictionary, not a List.
var dict = new Dictionary<string, int>();
dict.Add("current", 10);
dict.Add("target", 15);
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The question is on C#.
I have a string "value1=1234;value2=2345;value3=3456;value4= ..."
What is the best way to retrieve the values?
I thought about String.Split(";") but I don't know how to retrieve the values only. The result I get includes the prefix I don't want.
I only want the values of "1234", "2345", "3456"... nothing else, and them put them into a list of strings.
How do I solve this? Thanks.
If the format is always fixed, you can do it fairly easily via LINQ:
List<string> values = theString.Split(';').Select(s => s.Split('=')[1]).ToList();
Note that you may want to use RemoveEmptyEntries if your input string ends in a semi-colon:
List<string> values = theString
.Split(new[]{';'}, StringSplitOptions.RemoveEmptyEntries)
.Select(s => s.Split('=')[1]).ToList();
This would prevent an exception from occuring within the Select. If the input doesn't end in a semi-colon, however, this wouldn't be necessary.
var text = "value1=1234;value2=2345;value3=3456;value4= ...";
var pieces = text.Split('=');
var values = new Dictionary<string,string>();
for(int index = 0; index < pieces.Length; index += 2)
{
values.Add(pieces[index], pieces[index + 1]);
}
This will give you a dictionary of the pairs where the key is the left-hand side of the '=' and the value is the string representation of the value, which allows your to do:
var value1 = values["value1"];
var value2 = values["value2"];
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How can I serialize a string like this: "Yes,No" into something like this {"0":"Yes", "1":"No"} ?
I have split the string by ',' and I've stored value into a KeyValuePair<int,string>. After serialization, the result is something like this:
{"Key" : "0" , "Value" : "Yes"},{"Key":"1","Value":"No"}
var result = yourString.Split(',').Select((v, k) => new { k, v, })
.ToDictionary(a => a.k, a => a.v);
You could always just serialize it yourself:
string theString = "True,False";
var result = theString.Split(',')
.Select((v, i) => string.Format("\"{0}\":\"{1}\"", i, v));
To get the final result you're asking for you could do this:
String.Join(",", input.Split(',')
.Select((s,i) => "{\"Key\":\""+i+"\",\"Value\":\""+s+"\"}"));
string s = "yes,no";
var d = s.Split(',');
var result = new Dictionary<int,string>(){};
for (int i = 0; i < d.Length; i++) {
result.Add(i, d[i]);
}
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How apply linq select to string array in C#
ex :
string[] result;
...
result.Select(..)
?
Thanks.
You pass in a lambda function that tells the system what you want to do with each string.
string[] result;
...
var newList = result.Select(s => {do something with s});
The function can do most anything that takes a string as an input and returns a value - it doesn't even have to return a string! For example, if the strings contained numeric characters, you could return a collection of numbers:
IEnumerable<int> newList = result.Select(s => int.Parse(s));
Note that the original array will not be changed.