C# String StartsWith() Method

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.

True
False

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.

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.

GeekforGeeks Computer Science Portal </p>
GeekforGeeks Sudo Placement </h1>
GeekforGeeks Placement Preparation </h2>
GeekforGeeks Contribute 
GeekforGeeks Interview </h5>

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:

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: