"Go Language" "5" Go language variable

This is a creation in Article, where the information may have evolved or changed.

Variables are also the basic elements of language, similar to the constants of the go language, constants are decorated with the Const keyword, and variables are decorated with the var keyword, and the variable declaration is in the form of var variableName variabletype

First, variable declaration

var age int

var phone int

var name string

var address string

var salary float64

var consume float64

var array [10]int

var frieds [20]string

Each variable declaration uses a var, can the above example reduce the number of Var? The previous said go is the most programmer-savvy, so of course, can be abbreviated as:

VAR (

Listen to age and listen to int

Listen to the phone and listen int

Listen to the name and listen to the string

Listen to the address string

Listen to salary listen to float64

Listen to consume float64

Listen to array listen [10]int

Listen to Frieds listen to [20]string

)

Although the above is declared with only one Var, but the number of rows of the variable is not reduced, the attentive reader may find that there are two int, two string, and two float64, can it be merged? The answer can be:

VAR (

Listen to age, phone listen int

Listen to name, address listen to string

Listen to salary, consume listen to float64

Listen to array listen and hear [10]int

Listen to Frieds listen and hear [20]string

)

When the type is the same, you can press var variable1,variable2,variable3,variable4 listen Variabletype This form declares

Second, the default value when declaring a variable

1. Variable default value

Run the above program can find the int variable default assignment to 0,string variable default assignment is empty string (so print out invisible), float64 variable default assignment to 0,int array of each element default assignment to the 0,string array default assignment to the empty string

Although there is no complex type defined in this example, it is not difficult to infer that the complex variable is assigned the default value 0+0i

2, the essence of the variable declaration

A variable declaration is essentially a request for a piece of data storage space and name it, so that the program can use the variable name of the storage space, the go compiler in the variable declaration by the way of assigning a default value

Third, variable initialization

As the example above shows, the compiler assigns a value by default when the variable is declared, but this value may not be what we want, so we can initialize the variable at the same time as the declaration, in the form of var variableName variabletype = value

var age int = 22

var phone int = 13581887557

var name string = "correct elder brother"

var address string = "Shandong"

var salary float64 = 3030.30

var consume float64 = 1552.8

var array [10]int = [10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

var frieds [3]string = [3]string{"Shandong", "Li Dabong", "13581887557"}

Similar to a variable declaration, you can save the number of Var:

VAR (

Listen to age listen int listen to listen = 22

Listen to the phone listen int listen to listen = 13581887557

Listen to the name listen to string listen = "correct brother"

Listen to address string listen = "Shandong"

Listen salary listen to float64 listen = 3030.30

Listen consume float64 listen = 1552.8

Listen to array listen [10]int listen = [10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

Listen frieds [3]string = [3]string{"Shandong", "Li Dabong", "13581887557"}

)

You can also reduce the number of rows:

VAR (

Listen to age, phone listen int listen to listen = 22, 13581887557

Listen to the name, address listen to string listen = "correct elder brother", "Shandong"

Listen to salary, consume float64 listen = 3030.30, 1552.8

Listen to array listen [10]int listen = [10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

Listen frieds [3]string = [3]string{"Shandong", "Li Dabong", "13581887557"}

)

You can also remove variable types:

VAR (

Listen to age, phone listen = 22, 13581887557

Listen to name, address listen = "correct elder brother", "Shandong"

Listen to salary, consume = 3030.30, 1552.8

Listen to array listen = [10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

Listen to frieds listen = [3]string{"Shandong", "Li Dabong", "13581887557"}

)

Is there any more ruthless? Readers ' eyes:

Age, Phone: = 22, 13581887557

Name, Address: = "correct elder brother", "Shandong"

Salary, consume: = 3030.30, 1552.8

Array: = [10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

Frieds: = [3]string{"Shandong", "Li Dabong", "13581887557"}

Run, the small partners are stunned, so it is also OK, yes, go language is so wayward

Iv. Assigning values of variables

The following is the assignment process after declaring a variable:

var name string

Name = "Qingke"

Example:

If both the variable A and the variable B are integral, where a has a value of 10,b of 12, and the write program swaps the values of A and B

var a, b int A, B = ten, //variable assignment Fmt. Println ("a =", A, "B =", b) A, B = B, a listen //A and B value interchange Fmt. Println ("a =", A, "B =", b)

Readers of the first contact with go may find that the digital exchange did not introduce intermediate variables! Yes, go is so willful

V. Variable declarations and initializers (: =)

" Example 1": First look at the applet

var value1 int32 = 22

value2: = 22

Fmt. Println (value1 = = value2)

Here first initializes the variable value1, which is of type int32, and then uses: = character to declare and initialize the variable value2, and finally determine whether value1 and value2 are equal?

The result of the operation was unexpected, and an error was thrown: saying that the type of value2 does not match the type of value1, that is, when initializing the variable value2, the go compiler automatically derives an int type to value2 based on the value 22 of the variable; in the Go language int, Int32 and Int64 are considered to be of different types.

" Example 2": Look at a small program again

var a int

A: = 23

will the program compile with an error?

From the running result, the use of: = variable definition and initialization of the same time, the second variable A and the first variable a name conflict.

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