Interview questions on string functions in c#

 

What are the differences between String and StringBuilder in C#?

• String is immutable, meaning its value cannot be changed after creation. Operations like concatenation create new strings.
• StringBuilder is mutable and designed for efficient string manipulation. It allows modifications without creating new instances.

How do you check if two strings are equal in C#?

• Use the Equals() method or == operator to compare strings for equality. For instance:
• string str1 = "Hello"; string str2 = "Hello"; bool areEqual = str1.Equals(str2); // or bool areEqual = (str1 == str2);

Explain the difference between String.Substring() and String.Remove() methods.

• Substring() extracts a substring starting from a specified index and optional length.
• Remove() removes a specified number of characters starting from a specified index.

How can you reverse a string in C#?

• There are various approaches. One way is to convert the string to an array of characters, then reverse the array and convert it back to a string.
• string original = "Hello"; char[] charArray = original.ToCharArray(); Array.Reverse(charArray); string reversed = new string(charArray);

What is the purpose of String.Split() method?

• String.Split() divides a string into substrings based on a specified separator and returns an array of strings.
• string sentence = "Hello, how are you?"; string[] words = sentence.Split(' '); // Splits by space

How do you concatenate strings efficiently in C#?

• Use StringBuilder for concatenating multiple strings. It's more efficient than repeatedly concatenating with + operator or String.Concat() due to its mutability.
• StringBuilder sb = new StringBuilder(); sb.Append("Hello"); sb.Append(" "); sb.Append("World"); string result = sb.ToString();

Explain the usage of String.Format() method.

• String.Format() is used to format strings by inserting values into placeholders within a format string.
• int value = 42; string formatted = string.Format("The answer is {0}", value);
• // Outputs: "The answer is 42"

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  • How would you determine the length of a string in C#?

  • To get the length of a string in C#, I'd use the Length property.

  • For example:

  • string myString = 'Hello';

  • int length = myString.Length;

  • 


  • Can you explain the concept of string interpolation in C#?

  • String interpolation in C# allows embedding expressions directly within string literals, making it more readable. I'd use $ before the string and insert variables or expressions within curly braces.

  • For instance:

  • int num = 10;

  • string result = $"The number is {num}";