C # const detailed analysis and description

Const is a key word in C language. It specifies that a variable cannot be changed. Using const can improve the security and reliability of the program to a certain extent. In addition, it is helpful to understand the role of const while watching other people's code. In addition, const also appears in other programming languages, such as c ++, php tutorial 5, c #. net, hc08 c

The variable modified by const is a read-only variable.

The const definition should be that its value cannot be changed after initialization.

For example, const int a = 1; // It can only be initialized during definition;

A = 2; // an error occurs because a is a read-only variable.

Usage of const when modifying some pointers

Int;

Const int * p = & a; // * p cannot be changed, but p can be changed.

Int * const p1 // defines a read-only variable p1; p1 cannot be changed * p1 can be changed

A constant declaration can declare multiple constants, for example, public const double x = 1.0, y = 2.0, z = 3.0; static modifiers cannot be used in a constant declaration. Constants can be involved in constant expressions, as shown below: public const int c1 = 5; public const int c2 = c1 + 100; note that the readonly keyword is different from the const keyword. The const field can only be initialized in the declaration of this field. The readonly field can be initialized in the Declaration or constructor. Therefore, the readonly field may have different values based on the constructors used. In addition, the const field is the compile time, while the readonly field can be used for the run time, as shown in the following code line: public static readonly uint l1 = (uint) datetime. now. ticks;