2.4. Go language basic syntax

We already know about the last chapter. The basic structure of Go language, which we will learn in this chapter Go basic grammar of the language.

2.4.1. Go marker #

Go program can be composed of multiple tags, which can be keywords, identifiers, constants, strings, and symbols. As follows GO statement consists of six tags:

fmt.Println("Hello, World!") 

The 6 tags are (one per line):

1. fmt 2. . 3. Println 4. ( 5. "Hello, World!" 6. ) 

2.4.2. Line delimiter #

In Go a program, one line represents the end of a statement. Each statement does not need to be like C other languages in the family use semicolons as well. ; at the end, because all of this work will be done by Go compiler completes automatically.

If you plan to write multiple statements on the same line, they must use the ; artificial distinction, but in actual development, we do not encourage this practice.

Here are two statements:

fmt.Println("Hello, World!") fmt.Println("Novice Tutorial：runoob.com") 

2.4.3. Annotation #

Comments will not be compiled, and each package should have related comments.

Single-line comments are the most common form of comments, and you can use them anywhere with // single-line comment at the beginning. Multiline comments, also known as block comments, have been marked with /* start with a */ end. Such as:

// Single-Line Comments /* Author by Novice Tutorial I am a multi line comment */ 

2.4.4. Identifier #

Identifiers are used to name variables, types, and other program entities. An identifier is actually a sequence of one or more letters (AbeliZ and axiz) numbers (0,9) and underscores _, but the first character must be a letter or underscore, not a number.

The following are valid identifiers:

mahesh kumar abc move_name a_123 myname50 _temp j a23b9 retVal 

The following are invalid identifiers:

1ab (starts with a number)
case ( Go keywords of language)
a+b (operators are not allowed)

2.4.5. String concatenation #

The string of the Go language can be passed through the + :

Example #

package main import "fmt" func main() { fmt.Println("Google" + "Runoob") } 

The output result of the above example is:

GoogleRunoob

2.4.6. Keyword #

The following is listed Go 25 keywords or reserved words that will be used in the code:

Break	Default	Func	Interface	Select
Case	defer	Go	Map	Struct
Chan	Else	Goto	Package	switch
Const	Fallthrough	If	Range	Type
Continue	For	Import	Return	Var

In addition to the keywords introduced above Go language also has 36 predefined identifiers:

Append	Bool	Byte	Cap	Close	Complex	Complex64	Complex128	Uint16
Copy	False	Float32	Float64	Imag	Int	Int8	Int16	uint32
Int32	Int64	Iota	Len	Make	New	Nil	Panic	Uint64
Print	Println	Real	Recover	string	True	Uint	Uint8	Uintptr

Programs generally consist of keywords, constants, variables, operators, types, and functions.

These delimiters may be used in the program: parentheses () , square brackets [] and curly braces {} .

These punctuation marks may be used in the program: . , , , ; : and ... .

2.4.7. Spaces in Go language #

The declaration of variables in the Go language must be separated by spaces, such as:

var age int; 

The proper use of spaces in the statement can make the program easier to read.

No spaces:

fruit=apples+oranges; 

Add a space between variables and operators to make the program look more beautiful, such as:

fruit = apples + oranges; 

2.4.8. Format string #

Go use in language fmt.Sprintf format the string and assign a value to the new string:

Example #

package main import ( "fmt" ) func main() { // %d represents an integer number, %s represents a string var stockcode=123 var enddate="2020-12-31" var url="Code=%d&endDate=%s" var target_url=fmt.Sprintf(url,stockcode,enddate) fmt.Println(target_url) } 

The output is as follows:

Code=123&endDate=2020-12-31 