List<T>.Sort() Method is used to sort the elements or a portion of the elements in the List<T> using either the specified or default IComparer<T> implementation or a provided Comparison<T> delegate to compare list elements. There are total 4 methods in the overload list of this method as follows:
- Sort(IComparer<T>)
- Sort(Int32, Int32, IComparer)
- Sort()
- Sort(Comparison<T>)
Here, we will discuss the first two methods.
Sort(IComparer<T>) Method
This method is used to sort the elements in the entire List<T> using the specified comparer.
Syntax:
public void Sort (System.Collections.Generic.IComparer<T> comparer);
Here, the comparer is the IComparer<T> implementation to use when comparing elements, or null to use the default comparer Default.
Exceptions:
- InvalidOperationException: If the comparer is null, and the default comparer Default cannot find the implementation of the IComparable<T> generic interface or the IComparable interface for type T.
- ArgumentException: If the implementation of comparer caused an error during the sort. For example, comparer might not return 0 when comparing an item with itself.
Example 1:
// C# program to demonstrate the concept of // List<T>.Sort(IComparer <T>) method using System;
using System.Collections.Generic;
class GFG : IComparer< int >
{ public int Compare( int x, int y)
{
if (x == 0 || y == 0)
{
return 0;
}
// CompareTo() method
return x.CompareTo(y);
}
} public class geek
{ // Main Method
public static void Main()
{
// List initialize
List< int > list1 = new List< int >
{
// list elements
1,5,6,2,4,3
};
Console.WriteLine( "Original List" );
foreach ( int g in list1)
{
// Display Original List
Console.WriteLine(g);
}
// "gg" is the object oif class GFG
GFG gg = new GFG();
Console.WriteLine( "\nSort with a comparer:" );
// use of List<T>.Sort(IComparer<T>)
// method. The comparer is "gg"
list1.Sort(gg);
foreach ( int g in list1 )
{
// Display sorted list
Console.WriteLine(g);
}
}
} |
Original List 1 5 6 2 4 3 Sort with a comparer: 1 2 3 4 5 6
Example 2:
// C# program to demonstrate the concept of // List<T>.Sort(IComparer <T>) method using System;
using System.Collections.Generic;
class GFG : IComparer< string >
{ public int Compare( string x, string y)
{
if (x == null || y == null )
{
return 0;
}
// "CompareTo()" method
return x.CompareTo(y);
}
} public class geek
{ // Main Method
public static void Main()
{
List< string > list1 = new List< string >();
// list elements
list1.Add( "A" );
list1.Add( "I" );
list1.Add( "G" );
list1.Add( "B" );
list1.Add( "E" );
list1.Add( "H" );
list1.Add( "F" );
list1.Add( "C" );
list1.Add( "J" );
Console.WriteLine( "Original List" );
// Display Original List
Display(list1);
// "gg" is the object
GFG gg = new GFG();
Console.WriteLine( "\nSort with a comparer:" );
// sort the list with a
// specified comparer "gg"
list1.Sort(gg);
// Display sorted List
Display(list1);
Console.WriteLine( "\nBinarySearch and Insert D" );
// Binary Search for "D"
// using List.BinarySearch(T) method
int index = list1.BinarySearch( "D" );
if (index < 0)
{
// range++;
list1.Insert(~index, "D" );
}
// Display the List after
// inserting "D"
Display(list1);
}
// Display function
public static void Display(List< string > list)
{
foreach ( string g in list )
{
Console.WriteLine(g);
}
}
} |
Original List A I G B E H F C J Sort with a comparer: A B C E F G H I J BinarySearch and Insert D A B C D E F G H I J
List<T>.Sort(Int32, Int32, IComparer<T>) Method
This method is used to sort the elements in a range of elements in List<T> using the specified comparer.
Syntax:
public void Sort(int index, int len, IComparer<T> comparer)
Parameters:
index : It is the zero-based starting index of the range in which sort will happen.
len : It is the length of the range.
comparer : When comparing elements then use the IComparer implementation or null to use the default comparer Default.
Exceptions:
- ArgumentOutOfRangeException : If indexor len is less than 0.
- ArgumentException : If index and count do not specify a valid range in the List.
- InvalidOperationException : If comparer is null.
Example:
// C# program to demonstrate the use of // List<T>.Sort(Int32, Int32, IComparer<T>) // Method using System;
using System.Collections.Generic;
class GFG : IComparer< string >
{ public int Compare( string x, string y)
{
if (x == null || y == null )
{
return 0;
}
// "CompareTo()" method
return x.CompareTo(y);
}
} public class geek
{ public static void Main()
{
List< string > list1 = new List< string >();
// list elements
list1.Add( "C++" );
list1.Add( "Java" );
list1.Add( "C" );
list1.Add( "Python" );
list1.Add( "HTML" );
list1.Add( "CSS" );
list1.Add( "Scala" );
list1.Add( "Ruby" );
list1.Add( "Perl" );
int range = 4;
Console.WriteLine( "Original List" );
// Display Original List
Display(list1);
// "gg" is the object
GFG gg = new GFG();
Console.WriteLine( "\nSort a range with comparer:" );
// sort the list within a
// range of index 1 to 4
// where range = 4
list1.Sort(1, range, gg);
// Display sorted List
Display(list1);
Console.WriteLine( "\nBinarySearch and Insert Dart" );
// Binary Search and storing
// index value to "index"
int index = list1.BinarySearch(0, range,
"Dart" , gg);
if (index < 0)
{
list1.Insert(~index, "Dart" );
range++;
}
// Display the List
// after inserting "Dart"
Display(list1);
}
// Display function
public static void Display(List< string > list)
{
foreach ( string g in list)
{
Console.WriteLine(g);
}
}
} |
Original List C++ Java C Python HTML CSS Scala Ruby Perl Sort a range with comparer: C++ C HTML Java Python CSS Scala Ruby Perl BinarySearch and Insert Dart C++ C Dart HTML Java Python CSS Scala Ruby Perl
Reference: