Substring in C#

string str = "Hello World";
string substr1 = str.Substring(0, 5); // substr1 will contain "Hello"
string substr2 = str.Substring(6);    // substr2 will contain "World"

// A long string    
string bio = "Mahesh Chand is a founder of C# Corner. Mahesh is also an author, speaker, and software architect. Mahesh founded C# Corner in 2000.";    
    
// Get first 12 characters substring from a string    
string authorName = bio.Substring(0, 12);    
Console.WriteLine(authorName);

// Get everything else after 12th position     
string authorBio = bio.Substring(12);    
Console.WriteLine(authorBio);

using System;    
class Program    
{    
    static void Main(string[] args)    
    {    
        // A long string    
        string bio = "Mahesh Chand is a founder of C# Corner. Mahesh is also an author, " +    
            "speaker, and software architect. Mahesh founded C# Corner in 2000.";    
    
        // Get first 12 characters substring from a string    
        string authorName = bio.Substring(0, 12);    
        Console.WriteLine(authorName);    
    
        // Get everything else after 12th position     
        string authorBio = bio.Substring(12);    
        Console.WriteLine(authorBio);    
    
        Console.ReadKey();    
    }    
}

Figure 1.

3. Get a substring with a start and end index

The Substring method's first parameter is the substring's starting index. The second parameter is the number of characters, including whitespaces. Finally, you can use the String. Length to find out the end index of a string.

The following code snippet gets a substring from index eight until the string's end.

// Get a string between a start index and end index    
string str = "How to find a substring in a string";    
int startIndex = 7;    
int endIndex = str.Length - 7;    
string title = str.Substring(startIndex, endIndex);    
Console.WriteLine(title);

You can also pass the second argument of Substring to get several characters. For example, the following code snippet gets a substring of 15 characters starting at index 8.

// Get next 15 characters from starting index    
string title15 = str.Substring(startIndex, 15);

The output looks like Figure 2.

Figure 2.

4. Get a substring after or before a character in C#

You can use the Substring method to find a substring before the first occurrence of a specified character. You can pass the starting index as 0 and length as the position of the specified characters.

The following code snippet retrieves a substring before a comma's first occurrence.

// Get a substring after or before a character    
string authors = "Mahesh Chand, Henry He, Chris Love, Raj Beniwal, Praveen Kumar";            
string stringBeforeChar = authors.Substring(0, authors.IndexOf(","));            
Console.WriteLine(stringBeforeChar);

The following code snippet retrieves a substring after a comma's first occurrence.

// Get a substring after a character     
string stringAfterChar = authors.Substring(authors.IndexOf(",") + 2);    
Console.WriteLine(stringAfterChar);

5. Find the occurrence of substrings in a string in C#

You can find the position of a substring in a string by using String.IndexOf method. The following code snippet returns the position of a substring in a string.

int firstStringPosition = authors.IndexOf("Henry");

6. Get a substring between two strings in C#

You can use the Substring method to find a substring between two strings. First, you need to find the position of the two strings in the string. Then use the first string position as the starting position and find the string's length by subtracting the first string's position from the second string's position.

The following code snippet retrieves a substring between ‘Henry’ and ‘Beniwal’.

// Get a substring after or before a character    
string authors = "Mahesh Chand, Henry He, Chris Love, Raj Beniwal, Praveen Kumar";            
    
// Get a substring between two strings     
int firstStringPosition = authors.IndexOf("Henry");    
int secondStringPosition = authors.IndexOf("Beniwal");    
string stringBetweenTwoStrings = authors.Substring(firstStringPosition,     
    secondStringPosition - firstStringPosition + 7);    
Console.WriteLine(stringBetweenTwoStrings);

The substring includes both strings as well. If you want to exclude the two strings, ‘Henry’ and ‘Beniwal’, from the substring, you can increase the starting position and reduce the length parameters in the Substring method.

7. Split a string into substrings separated by a character in C#

We can use String. Split method to separate a string into an array of strings. You can also further search for a character in a string and retrieve a substring from it.

The following code snippet splits a string into an array of substrings that are separated by a comma. After that, the Substring method is further used to retrieve substrings followed by ‘:’ from the substring.

// Extract value of each attribute    
string author = "Name: Mahesh Chand, Book: C# Programming, Publisher: C# Corner, Year: 2020";    
string[] authorInfo = author.Split(", ");    
foreach (string info in authorInfo)    
{    
    Console.WriteLine("   {0}", info.Substring(info.IndexOf(": ") + 1));    
}

How do I get the last 4 characters of a string in C#?

This code snippet returns the last 4 characters of a string in C#. You can replace 5 with any number n to get the last n numbers of a string in C#.

string author = "Mahesh Chand is founder of C# Corner";  
string substr = author[^4..];  

Summary

This article and code sample taught us about substrings in C# and how to use String.Substring method to retrieve various types of substrings.

To learn more about C# strings, check out the String In C# tutorial to learn more about strings and how to work with strings in C#.