C# is a multi-paradigm programming language encompassing strong typing, imperative, declarative, functional, generic, object-oriented (class-based) and component-oriented programming disciplines. It was developed by Microsoft within its .NET initiative, and later approved as a standard by Ecma International (ECMA-334) and ISO (ISO/IEC 23270:2006). C# is one of the programming languages designed for the Common Language Infrastructure.
C# is intended to be a simple, modern, general-purpose, object-oriented programming language. Anders Hejlsberg leads its development team, and the most recent version is C# 5.0, which was released on August 15, 2012.
There are several hidden features of C#—tricks many C# fans, addicts and experts don’t even know—including the modulus (%) and null-coalescing (??) operators, goto statement, DefaultValue attribute, and the var type.
The following sections will describe these hidden features, and include example code to demonstrate each of them.
Modulus (%) Operator
The Modulus (%) operator computes the remainder after dividing its first operand by its second. All numeric types have predefined remainder operators. In the following snippet if myNumber is an even number, then its remainder is 0 when applying the Modulus operator. If myNumber is an odd number, then its remainder would be 1 when applying the Modulus operator.
number % 2
Null-coalescing (??) Operator
The null-coalescing (??) operator returns the left-hand operand if the operand is not null; otherwise it returns the right hand operand.
In the following code snippet the variable useNumber is set equal to number if number is NOT null. If number is null, then useNumber is set equal to -99.
var useNumber = number ?? -99;
The goto statement transfers the program control directly to a labeled statement.
A common use of goto is to transfer control to a specific switch-case label or the default label in a switch statement.
The goto statement is also useful to get out of deeply nested loops.
In the code snippet below, goto is used to direct the control flow of the program to the even: label if useNumber is an even number; and to the odd: label if useNumber is an odd number, as determined by the Modulus operation.
The DefaultValue specifies the default value for a property. It is useful when one wants to have a known default value for a property.
Variables that are declared at method scope can have an implicit type var. An implicitly typed local variable is strongly typed—just as if you had declared the type yourself, but the compiler determines the type.
Use of the var type makes code easier to read. In the following code snippet the variable _two would be of integer type.
var _two = 2;
The following code block demonstrates a code block that contains three goto statements. In this code block the integer (number) passed in is tested for whether it is null using the null-coalescing (??) operator. If it is null, the goto myEnd: statement passes control to the myEnd: label and the function returns “You passed a null value to this function” to the calling program.
If the integer is not null, the number is tested for evenness using the modulus operator (%). If it has no remainder from the modulus operation, the goto even: statement passes control to the even: label and the function returns “You are an EVEN number” to the calling program.
If the number has a remainder from using the modulus operator (%), the goto odd: statement passes control to the odd: label and returns “You are an ODD number” to the calling program.
The code block contains a property decorated with the DefaultValue Attribute with a value of 2.
Knowing and understanding obscure C# coding features allows you to solve more business problems.