C# is a powerful programming language that offers a wide range of built-in methods and functions to simplify programming tasks and provide ready-to-use functionality. These built-in methods/functions are part of the .NET Framework and cover various areas such as console input/output, mathematical operations, string manipulation, working with arrays, and more. In this response, we will explore some of the important and commonly used built-in methods/functions in C#.
1. `System.Math`:
| Method |
Description |
Example |
| Abs() |
Returns the absolute value of a number. |
int absoluteValue = Math.Abs(-10); // Result: 10 |
| Ceiling() |
Rounds a decimal value to the nearest greater or equal integer. |
double roundedUp = Math.Ceiling(4.3); // Result: 5 |
| Floor() |
Rounds a decimal value to the nearest smaller or equal integer. |
double roundedDown = Math.Floor(4.8); // Result: 4 |
| Max() |
Returns the larger of two numbers. |
int largest = Math.Max(10, 20); // Result: 20 |
| Min() |
Returns the smaller of two numbers. |
int smallest = Math.Min(10, 20); // Result: 10 |
| Pow() |
Calculates the power of a number. |
double result = Math.Pow(2, 3); // Result: 8 |
| Round() |
Rounds a decimal value to the nearest integer or a specified number of decimal places. |
double roundedValue = Math.Round(4.6); // Result: 5 |
| Sqrt() |
Calculates the square root of a number. |
double result = Math.Sqrt(25); // Result: 5 |
2. `System.String`:
| Method |
Description |
Example |
| Compare() |
Compares two strings and returns an integer that indicates their relative position in the sort order. |
int comparisonResult = String.Compare("apple", "banana"); // Result: -1 |
| Concat() |
Concatenates one or more strings into a single string. |
string firstName = "John"; string lastName = "Doe"; string fullName = String.Concat(firstName, " ", lastName); // Result: "John Doe" |
| Length |
Returns the length of the string. |
string str = "Hello"; int length = str.Length; // Result: 5 |
| Substring() |
Returns a substring of the original string. |
string str = "Hello World"; string subStr = str.Substring(6); // Result: "World" |
| ToLower() |
Converts the string to lowercase. |
string str = "Hello"; string lowerStr = str.ToLower(); // Result: "hello" |
| ToUpper() |
Converts the string to uppercase. |
string str = "Hello"; string upperStr = str.ToUpper(); // Result: "HELLO" |
| Trim() |
Removes leading and trailing white spaces from the string. |
string str = " Hello "; string trimmedStr = str.Trim(); // Result: "Hello" |
| IndexOf() |
Returns the index of the first occurrence of a substring. |
string str = "Hello World"; int index = str.IndexOf("World"); // Result: 6 |
3. `System.Array`:
| Method |
Description |
Example |
| Sort() |
Sorts the elements of an array. |
int[] numbers = { 5, 2, 1, 3, 4 }; Array.Sort(numbers); |
| Length |
Returns the length of the array. |
int[] numbers = { 5, 2, 1, 3, 4 }; int length = numbers.Length; |
| Reverse() |
Reverses the sequence of the elements in the entire one-dimensional Array. |
int[] numbers = { 5, 2, 1, 3, 4 }; Array.Reverse(numbers); // numbers: {4, 3, 1, 2, 5} |
| Copy() |
Creates a copy of the Array. |
int[] numbers = { 5, 2, 1, 3, 4 }; int[] copyOfNumbers = new int[numbers.Length]; Array.Copy(numbers, copyOfNumbers, numbers.Length); |
| BinarySearch() |
Searches an array for a specific value using the binary search algorithm. |
int[] numbers = { 1, 2, 3, 4, 5 }; int index = Array.BinarySearch(numbers, 3); // index: 2 |
4. `System.DateTime`:
| Method |
Description |
Example |
| Now |
Gets the current date and time. |
DateTime now = DateTime.Now; |
| AddDays() |
Adds a specified number of days to a date. |
DateTime tomorrow = DateTime.Now.AddDays(1); |
| ToString() |
Converts the date and time value to a string representation. |
DateTime now = DateTime.Now; string dateString = now.ToString("yyyy-MM-dd HH:mm:ss"); |
