Is there an easy way to convert a string array into a concatenated string?
For example, I have a string array:
new string[]{"Apples", "Bananas", "Cherries"};
And I want to get a single string:
"Apples,Bananas,Cherries"
Or "Apples&Bananas&Cherries" or "Apples\Bananas\Cherries"
A simple one...
string[] theArray = new string[]{"Apples", "Bananas", "Cherries"};
string s = string.Join(",",theArray);
The obvious choise is of course the String.Join method.
Here's a LINQy alternative:
string.Concat(fruit.Select((s, i) => (i == 0 ? "" : ",") + s).ToArray())
(Not really useful as it stands as it does the same as the Join method, but maybe for expanding where the method can't go, like alternating separators...)
String.Join Method (String, String[])
You can use Aggregate, it applies an accumulator function over a sequence.
string[] test = new string[]{"Apples", "Bananas", "Cherries"};
char delemeter = ',';
string joinedString = test.Aggregate((prev, current) => prev + delemeter + current);
Related
for long time , I always append a string in the following way.
for example if i want to get all the employee names separated by some symbol , in the below example i opeted for pipe symbol.
string final=string.Empty;
foreach(Employee emp in EmployeeList)
{
final+=emp.Name+"|"; // if i want to separate them by pipe symbol
}
at the end i do a substring and remove the last pipe symbol as it is not required
final=final.Substring(0,final.length-1);
Is there any effective way of doing this.
I don't want to appened the pipe symbol for the last item and do a substring again.
Use string.Join() and a Linq projection with Select() instead:
finalString = string.Join("|", EmployeeList.Select( x=> x.Name));
Three reasons why this approach is better:
It is much more concise and readable
– it expresses intend, not how you
want to achieve your goal (in your
case concatenating strings in a
loop). Using a simple projection with Linq also helps here.
It is optimized by the framework for
performance: In most cases string.Join() will
use a StringBuilder internally, so
you are not creating multiple strings that are
then un-referenced and must be
garbage collected. Also see: Do not
concatenate strings inside loops
You don’t have to worry about special cases. string.Join()
automatically handles the case of
the “last item” after which you do
not want another separator, again
this simplifies your code and makes
it less error prone.
I like using the aggregate function in linq, such as:
string[] words = { "one", "two", "three" };
var res = words.Aggregate((current, next) => current + ", " + next);
You should join your strings.
Example (borrowed from MSDN):
using System;
class Sample {
public static void Main() {
String[] val = {"apple", "orange", "grape", "pear"};
String sep = ", ";
String result;
Console.WriteLine("sep = '{0}'", sep);
Console.WriteLine("val[] = {{'{0}' '{1}' '{2}' '{3}'}}", val[0], val[1], val[2], val[3]);
result = String.Join(sep, val, 1, 2);
Console.WriteLine("String.Join(sep, val, 1, 2) = '{0}'", result);
}
}
For building up like this, a StringBuilder is probably a better choice.
For your final pipe issue, simply leave the last append outside of the loop
int size = EmployeeList.length()
for(int i = 0; i < size - 1; i++)
{
final+=EmployeeList.getEmployee(i).Name+"|";
}
final+=EmployeeList.getEmployee(size-1).Name;
My ArrayList Object Contains 3 Values.
ArrayList arr=new ArrayList()
arr.Add("abc");
arr.Add("def");
arr.Add("ghi");
I've got the requirement to Separate the Values with a , Separator
So, I googled and got the solution as
string afterjoined=string.Join(",", (string[])arr.ToArray(Type.GetType("System.String")));
The above code will return as
abc,def,ghi
But the above code will not allow any string to be concatenated with it.
I want a Specific string that needs to be concatenated with the final, separated values like the below,
MYabc,MYdef,Myghi
Here what I tried with the existing code(Which is not working)
string afterjoined=string.Join(",", "MYabc"+(string[])arr.ToArray(Type.GetType("System.String")));
This is what you need:
string.Join(",",
arr.Cast<string>() // use cast here instead of the casting to reduce the number of ()s
.Select(x => "MY" + x))
The Select call transforms each of the strings in the list by doing your specified transformation. In this case, it's "MY" + x, so it will prefix MY to each of the elements in the array.
And why are you using ArrayLists? They are not type-safe. You should be using List<T> instead. The code will become much cleaner:
List<string> arr=new List<string>();
arr.Add("abc");
arr.Add("def");
arr.Add("ghi");
string joined = string.Join(",", arr.Select(x => "MY" + x));
I use this extension method (normally with generic IEnumerable, modified for ArrayList) if I need that functionality:
public static string MergeWithPrefix(this ArrayList list, string prefix, string separator = ";")
{
var sb = new StringBuilder(list.Count * 16);
foreach (var item in list)
sb.Append(prefix).Append(item).Append(separator);
sb.Remove(sb.Length - separator.Length, separator.Length);
return sb.ToString();
}
Sorry for the dumb question, but I am having a bit of trouble with this. I would like to return
"James, Sam, Amanda"
but I am getting
"{ nameA = James, nameB = Sam, NameC = Amanda },"
Little help for a slow guy?
string str = String.Join(",", lst.Select(s => new { s.nameA, s.nameB, s.nameC }));
String.Join concatenates all the elements of a string array, using the delimiter you provide.
So, just send your list to an array:
string str = String.Join(",",lst.ToArray());
Also:
string str = String.Join(",", new[] { s.nameA, s.nameB, s.nameC });
Assuming that you have a list of string
you can do
string str = String.Join(",",lst.ToArray());
if lst contains your names, you just need
string str = String.Join(", ", lst.ToArray());
Just use the string.Format instead of.
string result = string.Format("{0},{1},{2}", lst.ToArray());
for long time , I always append a string in the following way.
for example if i want to get all the employee names separated by some symbol , in the below example i opeted for pipe symbol.
string final=string.Empty;
foreach(Employee emp in EmployeeList)
{
final+=emp.Name+"|"; // if i want to separate them by pipe symbol
}
at the end i do a substring and remove the last pipe symbol as it is not required
final=final.Substring(0,final.length-1);
Is there any effective way of doing this.
I don't want to appened the pipe symbol for the last item and do a substring again.
Use string.Join() and a Linq projection with Select() instead:
finalString = string.Join("|", EmployeeList.Select( x=> x.Name));
Three reasons why this approach is better:
It is much more concise and readable
– it expresses intend, not how you
want to achieve your goal (in your
case concatenating strings in a
loop). Using a simple projection with Linq also helps here.
It is optimized by the framework for
performance: In most cases string.Join() will
use a StringBuilder internally, so
you are not creating multiple strings that are
then un-referenced and must be
garbage collected. Also see: Do not
concatenate strings inside loops
You don’t have to worry about special cases. string.Join()
automatically handles the case of
the “last item” after which you do
not want another separator, again
this simplifies your code and makes
it less error prone.
I like using the aggregate function in linq, such as:
string[] words = { "one", "two", "three" };
var res = words.Aggregate((current, next) => current + ", " + next);
You should join your strings.
Example (borrowed from MSDN):
using System;
class Sample {
public static void Main() {
String[] val = {"apple", "orange", "grape", "pear"};
String sep = ", ";
String result;
Console.WriteLine("sep = '{0}'", sep);
Console.WriteLine("val[] = {{'{0}' '{1}' '{2}' '{3}'}}", val[0], val[1], val[2], val[3]);
result = String.Join(sep, val, 1, 2);
Console.WriteLine("String.Join(sep, val, 1, 2) = '{0}'", result);
}
}
For building up like this, a StringBuilder is probably a better choice.
For your final pipe issue, simply leave the last append outside of the loop
int size = EmployeeList.length()
for(int i = 0; i < size - 1; i++)
{
final+=EmployeeList.getEmployee(i).Name+"|";
}
final+=EmployeeList.getEmployee(size-1).Name;
How do I convert a list to a string in C#?
When I execute toString on a List object, I get:
System.Collections.Generic.List`1[System.String]
Maybe you are trying to do
string combinedString = string.Join( ",", myList.ToArray() );
You can replace "," with what you want to split the elements in the list by.
Edit: As mentioned in the comments you could also do
string combinedString = string.Join( ",", myList);
Reference:
Join<T>(String, IEnumerable<T>)
Concatenates the members of a collection, using the specified separator between each member.
I am going to go with my gut feeling and assume you want to concatenate the result of calling ToString on each element of the list.
var result = string.Join(",", list.ToArray());
You could use string.Join:
List<string> list = new List<string>()
{
"Red",
"Blue",
"Green"
};
string output = string.Join(Environment.NewLine, list.ToArray());
Console.Write(output);
The result would be:
Red
Blue
Green
As an alternative to Environment.NewLine, you can replace it with a string based line-separator of your choosing.
String.Join(" ", myList) or String.Join(" ", myList.ToArray()). The first argument is the separator between the substrings.
var myList = new List<String> { "foo","bar","baz"};
Console.WriteLine(String.Join("-", myList)); // prints "foo-bar-baz"
Depending on your version of .NET you might need to use ToArray() on the list first..
If you want something slightly more complex than a simple join you can use LINQ e.g.
var result = myList.Aggregate((total, part) => total + "(" + part.ToLower() + ")");
Will take ["A", "B", "C"] and produce "(a)(b)(c)"
You have a List<string> - so if you want them concatenated, something like
string s = string.Join("", list);
would work (in .NET 4.0 at least). The first parameter is the delimiter. So you could also comma-delimit etc.
You might also want to look at using StringBuilder to do running concatenations, rather than forming a list.
The .ToString() method for reference types usually resolves back to System.Object.ToString() unless you override it in a derived type (possibly using extension methods for the built-in types). The default behavior for this method is to output the name of the type on which it's called. So what you're seeing is expected behavior.
You could try something like string.Join(", ", myList.ToArray()); to achieve this. It's an extra step, but it could be put in an extension method on System.Collections.Generic.List<T> to make it a bit easier. Something like this:
public static class GenericListExtensions
{
public static string ToString<T>(this IList<T> list)
{
return string.Join(", ", list);
}
}
(Note that this is free-hand and untested code. I don't have a compiler handy at the moment. So you'll want to experiment with it a little.)
It's hard to tell, but perhaps you're looking for something like:
var myString = String.Join(String.Empty, myList.ToArray());
This will implicitly call the ToString() method on each of the items in the list and concatenate them.
This method helped me when trying to retrieve data from Text File and store it in Array then Assign it to a string avariable.
string[] lines = File.ReadAllLines(Environment.CurrentDirectory + "\\Notes.txt");
string marRes = string.Join(Environment.NewLine, lines.ToArray());
Hopefully may help Someone!!!!
If you're looking to turn the items in a list into a big long string, do this: String.Join("", myList). Some older versions of the framework don't allow you to pass an IEnumerable as the second parameter, so you may need to convert your list to an array by calling .ToArray().
The direct answer to your question is String.Join as others have mentioned.
However, if you need some manipulations, you can use Aggregate:
List<string> employees = new List<string>();
employees.Add("e1");
employees.Add("e2");
employees.Add("e3");
string employeesString = "'" + employees.Aggregate((x, y) => x + "','" + y) + "'";
Console.WriteLine(employeesString);
Console.ReadLine();
This seems to work for me.
var combindedString = new string(list.ToArray());
If your list has fields/properties and you want to use a specific value (e.g. FirstName), then you can do this:
string combindedString = string.Join( ",", myList.Select(t=>t.FirstName).ToArray() );
string strs="111,222,333"
string.Join(",",strs.Split(',').ToList().Select(x=>x.PadLeft(6,'0')).ToArray());
The output
000111,000222,000333