The enumeration of Dark Horse programmer--c Language

First, the concept of enumerations

Enumerations are a basic data type in the C language, not a constructed type, which can be used to declare a set of constants. When a variable has several fixed possible values, the variable can be defined as an enumeration type.

For example, you can use a variable of an enumeration type to represent the season, because there are only 4 possible values for the season: Spring, summer, autumn, and winter.

II. definitions of enumeration types

The general form is: Enum enumeration Name {Enumeration element 1, Enumeration element 2,......};

1 enum Season {Spring, summer, autumn, winter};

Third, the definition of the enumeration variable

The preceding just defines the enumeration type, and next you can define the variable with the defined enumeration type, which, like the struct, has 3 ways of defining the enumeration variable

1. Define the enumeration type first, and then define the enumeration variables

1 enum Season {Spring, summer, autumn, winter}; 2 3 enum Season s;

2. Defining enumeration variables while defining enumeration types 1 enum Season {Spring, summer, autumn, winter} s;

3. Omit the enumeration name and define the enumeration variables directly 1 enum {Spring, summer, autumn, winter} s;

All three of the above are defined as enumeration variables s

Iv. Considerations for enumeration use

The 1> C language compiler handles enumeration elements (spring, summer, and so on) As Integer constants, called enumeration constants.

The value of the 2> enumeration element depends on the order in which the enumeration elements are arranged when defined. By default, the first enumeration element has a value of 0, the second is 1, and sequentially adds 1.

1#include <stdio.h>2 3 intMain ()4 {5     //1. Defining Enum Types6     enumSeason7     {8 Spring,9 Summer,Ten Autumn, One Winter A     }; -      -     //2. Defining enumeration Variables the     enumSeason s =Winter; -      -      -printf"%d\n", s); +      -      +     return 0; A}

Print Result: 3

That is, spring has a value of 0,summer value of 1,autumn and a value of 2,winter is 3

3> can also change the value of an enumeration element when defining an enumeration type

1#include <stdio.h>2 3 intMain ()4 {5     //1. Defining Enum Types6     enumSeason7     {8Spring =1,9 Summer,Ten Autumn, One Winter A     }; -      -     //2. Defining enumeration Variables the     enumSeason s =Winter; -      -      -printf"%d\n", s); +      -      +     return 0; A}

Print Result: 4

An enumeration element with no value specified, with a value of 1 for the previous element.

V. Basic operations of enumeration variables 1. Assigning values

Enumeration constants or integer values can be assigned to enumeration variables

1#include <stdio.h>2 3 intMain ()4 {5     //1. Defining Enum Types6     enumSeason {Spring, summer, autumn, winter} s;7     8     //2. Defining enumeration Variables9s = Spring;//equivalent to s = 0;Tenprintf"%d\n", s); One     As = Winter;//equivalent to S = 3; -printf"%d\n", s); -      the     return 0; -}

Printing results 0

3

2. Traversing an enumeration element

Enum Season {Spring, summer, autumn, winter} s;//traverse the enumeration element for (s = spring; s <= Winter; s++) {    printf ("enum element:%d \ n", s );}

Output Result: Enumeration element: 0

Enumeration elements: 1

Enumeration elements: 2

Enumeration elements: 3

Summary of data types

I. Basic data types

1.int

1> long int, long:8 bytes%ld

2> short int, short:2 bytes%d%i

3> unsigned int, unsigned:4 bytes%zd

4> signed int, signed, Int:4 byte%d%i

2.float\double

1> Float:4 bytes%f

2> Double:8 bytes%f

3.char

1> 1 bytes%c%d

The 2> char type is stored in memory with its ASCII value

' A '-65

Ii. Types of construction

1. Arrays

1> can only be made up of the same type of data

2> definition: Data type array name [number of elements];

2. Structural body

1> can be made up of different types of data

2> define the type, then use the type to define the variable

Third, pointer type

1. Definition of variables

int *p;

2. Value of the indirect action variable

int a = 10;

p = &a;

*p = 20;

Iv. Enumeration Type

Application: When a variable is allowed to have only a few fixed values

The enumeration of Dark Horse programmer--c Language