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C# Null and Empty Strings

In C#, a string can be null, empty (""), or consist of only whitespace. It's important to handle these cases to avoid exceptions.

Key Topics

1. Null vs. Empty Strings

A null string means it has not been assigned a value, while an empty string is a string with zero characters.

Example: Null and Empty Strings

string nullString = null;
string emptyString = "";
Console.WriteLine(nullString == null); // Outputs: True
Console.WriteLine(emptyString == "");   // Outputs: True

2. Checking for Null or Empty Strings

Example: Using String.IsNullOrEmpty()

string input = null;
bool isNullOrEmpty = String.IsNullOrEmpty(input);
Console.WriteLine(isNullOrEmpty); // Outputs: True

3. Using String.IsNullOrWhiteSpace()

This method checks if a string is null, empty, or consists only of whitespace characters.

Example: Checking for Whitespace Strings

string whitespaceString = "   ";
bool isNullOrWhiteSpace = String.IsNullOrWhiteSpace(whitespaceString);
Console.WriteLine(isNullOrWhiteSpace); // Outputs: True

Key Takeaways

  • A null string has not been assigned a value.
  • An empty string is a valid string with zero characters.
  • Use String.IsNullOrEmpty() and String.IsNullOrWhiteSpace() to safely check strings.
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