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C # includes built-in exception types such as NullReferenceException, MemoryOverflowException, and others. However, when the business rules of your application are violated, you usually want to throw an exception. Therefore, you can create a custom exception class by deriving from the ApplicationException class.
.Net version1Starting from .Net v
For example, in a school application, create the InvalidStudentNameException class that does not allow any student's name to contain any special characters or numeric values.
class Student
{"}}
public int StudentID { get; set; }
public string StudentName { get; set; }
}
[Serializable]
class InvalidStudentNameException : Exception
{"}}
public InvalidStudentNameException()
{"}}
}
public InvalidStudentNameException(string name)
: base(String.Format("Invalid Student Name: {0}", name))
{"}}
}
}Now, as long as the program name contains special characters or numbers, InvalidStudentNameException can be triggered in the program. Use the throw keyword to throw the exception.
class Program
{"}}
static void Main(string[] args)
{"}}
Student newStudent = null;
try
{"}}
newStudent = new Student();
newStudent.StudentName = "James00"7";
ValidateStudent(newStudent);
}
catch(InvalidStudentNameException ex)
{"}}
Console.WriteLine(ex.Message);
}
Console.ReadKey();
}
private static void ValidateStudent(Student std)
{"}}
Regex regex = new Regex("^[a-zA-Z]+$");
if (!regex.IsMatch(std.StudentName)) throw new InvalidStudentNameException(std.StudentName);
}
}Invalid Student Name: James000
Therefore, you can create custom exception classes to distinguish between system exceptions.