C# String Methods

This page introduces you to the most commonly used C# String methods, which allow you to manipulate strings effectively, including operations such as searching, replacing, formatting, and extracting substrings, among others.

Section 1. Searching

In this section, you will learn various string methods that search for a substring in a string.

Contains() – Returns true if the string contains the specified string, false otherwise.
IndexOf() – Returns the index of the first occurrence of the specified string in the string, or -1 if the string does not occur in the string.
LastIndexOf() – Returns the index of the specified string’s last occurrence, or -1 if the string does not occur in the string.
StartsWith() – Returns true if the string starts with the specified value, false otherwise.
EndsWith() – Returns true if the string ends with the specified value, false otherwise.

Section 2. Trimming

In this section, you’ll learn how to use various Trim* methods to remove the whitespace or a set of specified characters from a string:

Trim() – Returns a new string that is the same as the original string, but with any leading and trailing whitespace characters removed.
TrimStart() – Removes all whitespace characters at the beginning of the current string.
TrimEnd() – Removes all whitespace characters at the end of the current string.

Section 3. Padding

In this section, you will learn how to pad a string with specified characters to achieve a desired length.

PadLeft() – Returns a new string that is the specified length, with the specified character padded to the left.
PadRight() – Returns a new string that is the specified length, with the specified character padded to the right.

Section 4. Extracting

In this section, you will learn how to extract a portion of a string and split the string into an array of substrings:

Substring() – Returns a new string that is a substring of the original string, starting at the specified index and with the specified length.
Split() – Returns an array of strings that are the result of splitting the string at each occurrence of the specified separator string.

Section 5. Replacing & Inserting

In this section, you’ll learn how to replace a substring in a string with a new one:

Replace – Returns a new string with all occurrences of the specified old value replaced with the specified new value.
Insert() – Returns a new string with a string inserted at a specified index of the current string.

Section 6. Changing Cases

In this section, you’ll learn how to convert a string to lowercase or uppercase:

ToLower() – Returns a lowercase version of the string as a new copy.
ToUpper() – Returns an uppercase version of the string as a new copy.

Section 7. Concatenating

In this section, you’ll learn how to use the Join() and Concat() methods to concatenate two or more strings into a single string:

Join() – concatenate two or more strings in a collection into a string with a specified separator.
Concat() – concatenate two more strings into a string.

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