CODEWITHSUNDEEP
c#
kobe
kobe

Reputation: 15835

Appending a string in a loop in effective way

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.

Upvotes: 12

Views: 43560

Answers (5)

BrokenGlass
BrokenGlass

Reputation: 160942

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:

  1. 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.

  2. 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

  3. 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.

Upvotes: 35

marklar
marklar

Reputation: 502

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;

Upvotes: 0

Jim Deville
Jim Deville

Reputation: 10672

For building up like this, a StringBuilder is probably a better choice.

Upvotes: 0

robert
robert

Reputation: 34418

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);
    }
}

Upvotes: 3

FiveTools
FiveTools

Reputation: 6030

I like using the aggregate function in linq, such as:

string[] words = { "one", "two", "three" };
var res = words.Aggregate((current, next) => current + ", " + next);

Upvotes: 4

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