C# | StringCollection Class

StringCollection class is a new addition to the .NET Framework class library that represents a collection of strings. StringCollection class is defined in the System.Collections.Specialized namespace.

Characteristics:

• StringCollection class accepts null as a valid value and allows duplicate elements.
• String comparisons are case-sensitive.
• Elements in this collection can be accessed using an integer index.
• Indexes in this collection are zero-based.

Constructors

Constructor	Description
StringCollection()	Initializes a new instance of the StringCollection class.

Example:

// C# code to create a StringCollection
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // creating a StringCollection named myCol
        StringCollection myCol = new StringCollection();

        // Adding elements in StringCollection
        myCol.Add("A");
        myCol.Add("B");
        myCol.Add("C");
        myCol.Add("D");
        myCol.Add("E");

        // Displaying objects in myCol
        foreach(Object obj in myCol)
        {
            Console.WriteLine(obj);
        }
    }
}

Output:

A
B
C
D
E

Properties

Property	Description
Count	Gets the number of strings contained in the StringCollection.
IsReadOnly	Gets a value indicating whether the StringCollection is read-only.
IsSynchronized	Gets a value indicating whether access to the StringCollection is synchronized (thread safe).
Item[Int32]	Gets or sets the element at the specified index.
SyncRoot	Gets an object that can be used to synchronize access to the StringCollection.

Example:

// C# code to illustrate the StringCollection
// Class Properties
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // creating a StringCollection named myCol
        StringCollection myCol = new StringCollection();

        // creating a string array named myArr
        String[] myArr = new String[] { "A", "B", "C", "D", "E" };

        // Copying the elements of a string
        // array to the end of the StringCollection.
        myCol.AddRange(myArr);

        // --------- Using IsReadOnly Property ---------

        // checking if StringCollection is
        // read-only
        Console.WriteLine(myCol.IsReadOnly);

        // --------- Using Count Property ---------

        // To get number of Strings contained
        // in the StringCollection
        Console.WriteLine("Number of strings in myCol are : "
                                              + myCol.Count);
    }
}

Output:

False
Number of strings in myCol are : 5

Methods

Method	Description
Add(String)	Adds a string to the end of the StringCollection.
AddRange(String[])	Copies the elements of a string array to the end of the StringCollection.
Clear()	Removes all the strings from the StringCollection.
Contains(String)	Determines whether the specified string is in the StringCollection.
CopyTo(String[], Int32)	Copies the entire StringCollection values to a one-dimensional array of strings, starting at the specified index of the target array.
Equals(Object)	Determines whether the specified object is equal to the current object.
GetEnumerator()	Returns a StringEnumerator that iterates through the StringCollection.
GetHashCode()	Serves as the default hash function.
GetType()	Gets the Type of the current instance.
IndexOf(String)	Searches for the specified string and returns the zero-based index of the first occurrence within the StringCollection.
Insert(Int32, String)	Inserts a string into the StringCollection at the specified index.
MemberwiseClone()	Creates a shallow copy of the current Object.
Remove(String)	Removes the first occurrence of a specific string from the StringCollection.
RemoveAt(Int32)	Removes the string at the specified index of the StringCollection.
ToString()	Returns a string that represents the current object.

Example:

// C# code to copy StringCollection to array,
// starting at the specified index of
// the target array
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // creating a StringCollection named myCol
        StringCollection myCol = new StringCollection();

        // creating a string array named myArr1
        String[] myArr1 = new String[] { "A", "B", "C", "D", "E" };

        // Copying the elements of a string
        // array to the end of the StringCollection.
        myCol.AddRange(myArr1);

        // creating a String array named myArr2
        String[] myArr2 = new String[myCol.Count];

        // Copying StringCollection to array myArr2
        // starting from index 0
        myCol.CopyTo(myArr2, 0);

        // Displaying elements in array myArr2
        for (int i = 0; i < myArr2.Length; i++) {
            Console.WriteLine(myArr2[i]);
        }
    }
}

Output:

A
B
C
D
E

Example:

// C# code to insert a string into
// the StringCollection at the
// specified index
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // creating a StringCollection named myCol
        StringCollection myCol = new StringCollection();

        // creating a string array named myArr
        String[] myArr = new String[] { "Hello", "Geeks",
                                        "for", "GeeksforGeeks" };

        // Copying the elements of a string
        // array to the end of the StringCollection.
        myCol.AddRange(myArr);

        Console.WriteLine("Initially elements in StringCollection are: ");

        // Displaying elements in StringCollection
        // named myCol
        foreach(Object obj in myCol)
            Console.WriteLine(obj);

        // Removing all the elements from StringCollection
        myCol.Clear();

        Console.WriteLine("After Removing: ");

        // Displaying elements in StringCollection
        // named myCol
        foreach(Object obj in myCol)
            Console.WriteLine(obj);
    }
}

Output:

Initially elements in StringCollection are: 
Hello
Geeks
for
GeeksforGeeks
After Removing:

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.collections.specialized.stringcollection?view=netframework-4.7.2