A Go program consists of various tokens. A token is either a keyword, an identifier, a constant, a string literal, or a symbol. For example, the following Go statement consists of six tokens −
fmt.Println("Hello, World!") The individual tokens are −
fmt
.
Println
(
"Hello, World!"
)
##Line Separator In a Go program, the line separator key is a statement terminator. That is, individual statements don't need a special separator like “;” in C. The Go compiler internally places “;” as the statement terminator to indicate the end of one logical entity.
For example, take a look at the following statements −
fmt.Println("Hello, World!") fmt.Println("I am in Go Programming World!") Comments Comments are like helping texts in your Go program and they are ignored by the compiler. They start with /* and terminates with the characters */ as shown below −
/* my first program in Go */ You cannot have comments within comments and they do not occur within a string or character literals.
Identifiers A Go identifier is a name used to identify a variable, function, or any other user-defined item. An identifier starts with a letter A to Z or a to z or an underscore _ followed by zero or more letters, underscores, and digits (0 to 9).
identifier = letter { letter | unicode_digit }.
Go does not allow punctuation characters such as @, $, and % within identifiers. Go is a case-sensitive programming language. Thus, Manpower and manpower are two different identifiers in Go. Here are some examples of acceptable identifiers −
mahesh kumar abc move_name a_123 myname50 _temp j a23b9 retVal Keywords The following list shows the reserved words in Go. These reserved words may not be used as constant or variable or any other identifier names.
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 Whitespace in Go Whitespace is the term used in Go to describe blanks, tabs, newline characters, and comments. A line containing only whitespace, possibly with a comment, is known as a blank line, and a Go compiler totally ignores it.
Whitespaces separate one part of a statement from another and enables the compiler to identify where one element in a statement, such as int, ends and the next element begins. Therefore, in the following statement −
var age int; There must be at least one whitespace character (usually a space) between int and age for the compiler to be able to distinguish them. On the other hand, in the following statement −
fruit = apples + oranges; // get the total fruit No whitespace characters are necessary between fruit and =, or between = and apples, although you are free to include some if you wish for readability purpose.