Dark Horse programmer -02-Keywords, identifiers, annotations

One, the key word 1. What is a keyword

1> keyword is the C language provides a special meaning of the symbol, also known as "reserved word"

The 2> C language provides a total of 32 keywords, all of which are given special meaning by C language

Auto double int struct break else long switch

Case enum Register typedef char extern return Union

const float Short unsigned continue for signed void

Default goto sizeof volatile do if and static

2. Characteristics of keywords

1> are all lowercase

Special colors are displayed in the development tool or in the Smart Text Editing tool.

3. What are keywords in the main function

int, return

Second, the identifier 1. What is an identifier

Identifiers are some of the symbols and names that you customize in your program. To differentiate from keywords: the keyword is the symbol that is provided by the C language by default, and the identifier is a programmer-defined

2. The role of identifiers

1) identifiers, literally understood, are symbols used to identify something, the purpose of which is to separate it from the other.

2) In fact, the function of the identifier is similar to the human name, in order to distinguish each person, at the time of each person's birth a name

3) C language is composed of functions, a C program may have more than one function, in order to distinguish these functions, each function is given a name. The name of the function is one of the identifiers. In addition to the function, the concept of "variable" will be learned later, and the name of the variable is also the identifier

3. Naming

1> naming rules (be sure to follow)

L can only be made up of 26 letters in uppercase and lowercase, 10 Arabic numerals 0~9, underline _

L Strictly case-sensitive, such as test and test are 2 different identifiers

L cannot start with a number

L can not use keywords as identifiers

2> naming conventions (best to follow)

L try to make a meaningful name, such as a complete English word, the name can be seen by others to the role of this identifier. If you do not understand English, you can also use pinyin, try not to be like ABCDE, SFSDFSDF and other such seemingly meaningless names

L If the identifier contains more than one word, you can use the Hump logo (except for the first word, the first letter of each word is capitalized): FirstName, MyFirstName, or use the underscore _ to connect: first_name, My_first_name

Third, note 1. What is a comment

1) Annotations are a concept that is very important in all computer languages, literally, the meaning of annotations and explanations.

2) Comments can be used to explain the meaning of a program or a line of code to facilitate communication between programmers. If I finish writing a line of code and add the corresponding comment, then people will see this comment and know what my line of code is for.

3) Comments can be any text, which means you can write Chinese

4) Note in development tools is generally red bean paste Green

2. Single-line Comment

1) The single-line comment starts with two forward slashes, that is, starts with//, can only comment one line, from//start to the end of this line is the contents of the comment

2) anywhere you can write a comment: Outside the function, inside, behind each statement

3. Multi-line annotations

Multiline comments start with/*, end with */, the contents of/* and/* are commented

Dark Horse programmer -02-Keywords, identifiers, annotations