C# String StartsWith() Method (original) (raw)

Last Updated : 20 Mar, 2025

In C#, the **StartsWith() is a method of String Class. This method is used to check whether the beginning of the current string instance matches with a specified string or not. If it matches, it returns true; otherwise, it returns false. Using the foreach loop, we can check multiple strings. This method supports overloading by passing different types and numbers of arguments.

**Example: Basic use of StartsWith() method.

C# `

// C# program to illustrate the // String.StartsWith(String) Method using System;

public class Geeks { static public void Main() {

    String s = "GeeksforGeeks";

    // checking if the string starts with "Geeks"
    // returns true
    Console.WriteLine(s.StartsWith("Geeks"));

    // checking if the string starts with "geek"
    // returns false
    Console.WriteLine(s.StartsWith("geek"));

}

}

String.StartsWith(String)

This method is used to check whether the beginning of the string object matches a particular string or not. If it matches then it returns the string otherwise returns false.

**Syntax:

public bool StartsWith(string input_string)

**Parameter: It is a required string as **input_string which is to be compared and the type of this parameter is **System.String.
**Return Type: This function returns the _Boolean value. **True if it found a match, else it will return **false. The return type is **System.Boolean.
**Exception: If the input_string is Null then this method will give ArgumentNullException.

**Example 1: This program demonstrates the use of **String.StartsWith(String) method **to find the specified starting string.

C# `

// C# program to illustrate the // String.StartsWith(String) Method using System;

public class Geeks { static public void Main() {

    // The input string or character
    string SearchLink = "https://www.geeksforgeeks.org/placement-guide/";

    // Different string character and 
    // Possible string to be matches
    string[] allLinks = new string[] {
        "https://geeksforgeeks.org",
        "https://www.geeksforgeeks.org",
        "https://www.geeksforgeeks.org/placement"};

    // Using foreach - loop to check
    // each possible match
    foreach (string l in allLinks)
    {

        // To check match second possibility
        if (SearchLink.StartsWith(l))
        {

          
            Console.WriteLine("The SearchLink is started with the: "+l);
            return;
        }
    }
}

}

Output

The SearchLink is started with the: https://www.geeksforgeeks.org

**Explanation: In the above example, we use the StartsWith() method to to search if the SeachLink is started with the links present in the allLinks string array.

**Example 2: Another example demonstrates the use of the StartsWith() method of string class.

C# `

using System; class Geeks { public static void Main() { string[] inputStr = { "

GeekforGeeks Computer Science Portal

", "

GeekforGeeks Sudo Placement

", "

GeekforGeeks Placement Preparation

", "

GeekforGeeks Contribute ", "

GeekforGeeks Interview

" };

    foreach (var str in inputStr)
    {
        Console.WriteLine(RemoveHtmlTags(str));
    }
}

private static string RemoveHtmlTags(string str)
{
    // Here we use StartsWith() method to check 
    // if the string starts with "<" or not.
    // If it starts with "<" then we remove the
    // substring from the start to the first ">"
    while (str.Trim().StartsWith("<"))
    {
        int end = str.IndexOf(">");
        if (end >= 0)
        {
            str = str.Substring(end + 1);
        }
        else
        {
            break;
        }
    }
    return str;
}

}

Output

GeekforGeeks Computer Science Portal

GeekforGeeks Sudo Placement GeekforGeeks Placement Preparation GeekforGeeks Contribute GeekforGeeks Interview

**Explanation: In this example, we use the StartsWith() method to check if the string is started with the HTML tag and if it returns true we remove that HTML tag.

String.StartsWith(String, Boolean, CultureInfo)

This method is used to check whether the beginning of the current string instance matches the specified string when it is compared using the specified culture. If a match is found, then return the string otherwise return false.

**Syntax:

public bool StartsWith(string str, bool case, CultureInfo cul);

**Parameters: It takes three parameters which are:
- **str: It is the string which is to be compared and the type of this parameter is System.String.
- **case: It will set true to ignore case during the comparison, otherwise false and the type of this parameter is System.Boolean.
- **cul: It is the Cultural information which checks how current string and str are compared. If culture is null, the current culture is used and the type of this parameter is System.Globalization.CultureInfo.
**Return Value: This function returns the value of type System.Boolean that evaluates true if the str matches with the beginning of the current string else false.
**Exception: If the value of str is null then this method will give ArgumentNullException.

**Example:

C# `

// C# program to illustrate the // String.StartsWith (string, // bool, CultureInfo) Method using System.Threading; using System.Globalization; using System;

class Geeks { public static void Main(string[] args) {

    // Input string
    string s = "Geeks";

    // Implementation of startswith() function

    // test in original string.
    bool r1 = s.StartsWith("Geeks", false, 
                    CultureInfo.InvariantCulture);

    // test in small letter string.
    bool r2 = s.StartsWith("geeks", false, 
                    CultureInfo.InvariantCulture);

    // test in capital letter string.
    bool r3 = s.StartsWith("GEEKS", false, 
                    CultureInfo.InvariantCulture);

    // test in no string parameter .
    bool r4 = s.StartsWith(" ", false, 
                CultureInfo.InvariantCulture);

    Console.WriteLine("Is str started with Geeks: "+ r1);
    Console.WriteLine("Is str started with geeks: "+ r2);
    Console.WriteLine("Is str started with GEEKS: "+ r3);
    Console.WriteLine("Is str started with empty string: "+ r4);
}

}

Output

Is str started with Geeks: True Is str started with geeks: False Is str started with GEEKS: False Is str started with empty string: False

String.StartsWith(String, StringComparison)

This method is used to check whether the starting of the current string instance matches the specified string or not when compared using the specified comparison option. If a match is found, then it returns the string otherwise false.

**Syntax:

bool StartsWith(String str, StringComparison cType);

It takes two parameters which are:

**str: It is the required string which is to be compared and the type of this parameter is System.String.
**cType: It is one of the enumeration values that determine how the current string and str are compared. Type of this parameter is System.StringComparison.
**Return Value: This function returns the _Boolean value i.e. **true if it found a match, else it will return **false. Return type is _System.Boolean.

**Exceptions:

If the value of _str is null then this method will give _ArgumentNullException.
If the value of _cType is not a _StringComparison value then this method will give _ArgumentException.

**Example:

C# `

// C# program to illustrate the // StartsWith(String, StringComparison) // method using System;

class Geek {

// Main Method
public static void Main(string[] args)
{
    
    // Input two string
    string s1 = "GeeksforGeeks";
    string s2 = "Learn CSharp";

    // Implementation of startswith() function
    // test for original string1 value.
    bool r1 = s1.StartsWith("Geek", 
        StringComparison.CurrentCulture);
        
    // test for small letter string1 value .
    bool r2 = s1.StartsWith("geek", 
        StringComparison.CurrentCulture);

    // test for string2 value .
    bool r3 = s2.StartsWith("CSharp", 
            StringComparison.CurrentCulture);
            
    bool r4 = s2.StartsWith("Learn", 
        StringComparison.CurrentCulture);

    
    Console.WriteLine(r1);
    Console.WriteLine(r2);
    Console.WriteLine(r3);
    Console.WriteLine(r4);
}

}

Output

True False False True