having a List<int> of integers (for example: 1 - 3 - 4)
how can I convert it in a string of this type?
For example, the output should be:
string values = "1,3,4";
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6 Answers
var nums = new List<int> {1, 2, 3};
var result = string.Join(", ", nums);
var ints = new List<int>{1,3,4};
var stringsArray = ints.Select(i=>i.ToString()).ToArray();
var values = string.Join(",", stringsArray);
3 Comments
Ciupaz
Thank you Albin. E for the revers task, from a string of integer with commas, I need to obtain a List<int>. Luigi
Richard
In .NET 4
String.Join has an overload taking an IEnumerable<T> so this can be done without the intermediate array (this overload calls ToString() on each input element): string.Join(",", ints).
Albin Sunnanbo
@Ciupaz, for the reverse task, use
String.Split().Another solution would be the use of Aggregate. This is known to be much slower then the other provided solutions!
var ints = new List<int>{1,2,3,4};
var strings =
ints.Select(i => i.ToString(CultureInfo.InvariantCulture))
.Aggregate((s1, s2) => s1 + ", " + s2);
See comments below why you should not use it. Use String.Join or a StringBuilder instead.
3 Comments
Gert Arnold
-1 Notoriously bad solution to create strings like this (especially when the list is long). String.Join or StringBuilder are the way to go. Sad for Stack Overflow that a low quality OP does not even know how to accept the best answer.
Martijn
@GertArnold I agree with you. Just wanted to show another solution and forgot to mention anything performance. I tried to delete this answer but I can't. I will update the answer to not use it.
Ciupaz
Perfect, could be fine this wau. Thank you
public static string ToCommaString(this List<int> list)
{
if (list.Count <= 0)
return ("");
if (list.Count == 1)
return (list[0].ToString());
System.Text.StringBuilder sb = new System.Text.StringBuilder(list[0].ToString());
for (int x = 1; x < list.Count; x++)
sb.Append("," + list[x].ToString());
return (sb.ToString());
}
public static List<int> CommaStringToIntList(this string _s)
{
string[] ss = _s.Split(',');
List<int> list = new List<int>();
foreach (string s in ss)
list.Add(Int32.Parse(s));
return (list);
}
Usage:
String s = "1,2,3,4";
List<int> list = s.CommaStringToIntList();
list.Add(5);
s = list.ToCommaString();
s += ",6";
list = s.CommaStringToIntList();
1 Comment
R. Schreurs
Why did you post this alternate solution, when some very compact solutions using string.Join() had already been given?
You can use the delegates for the same
List<int> intList = new List<int>( new int[] {20,22,1,5,1,55,3,10,30});
string intStringList = string.Join(",", intList.ConvertAll<string>(delegate (int i) { return i.ToString(); });
Comments
Use the Stringify.Library nuget package
Example 1 (Default delimiter is implicitly taken as comma)
string values = "1,3,4";
var output = new StringConverter().ConvertFrom<List<int>>(values);
Example 2 (Specifying the delimiter explicitly)
string values = "1 ; 3; 4";
var output = new StringConverter().ConvertFrom<List<int>>(values), new ConverterOptions { Delimiter = ';' });
