C basic syntax

Tokens of C

C programs are composed of various tokens. Tokens can be keywords, identifiers, constants, string values, or a symbol. For example, the following C statement includes five tokens:

printf("Hello, World! \n");

The five tokens are:

printf("Hello, World! \n");

Semicolon;

In a C program, the semicolon Is the statement terminator. That is, each statement must end with a semicolon. It indicates the end of a logical entity.

For example, here are two different statements:

printf("Hello, World! \n");return 0;

Comments

Comments are like help text in C programs, they are ignored by the compiler. They start with /* and end with the character */, as shown below:

/* 我的第一个 C 程序 */

You cannot nest comments within comments, nor can comments appear within a string or character value.

Identifier

C Identifier is the name used to identify a variable, function, or any other user-defined item. An identifier begins with the letters A-Z or a-z or the underscore _, followed by zero or more letters, underscores, and numbers (0-9).

C Punctuation characters such as @, $, and % are not allowed within identifiers. C is a case-sensitive programming language. Therefore, in C, Manpower and manpower are two different identifiers. Several valid identifiers are listed below:

mohd       zara    abc   move_name  a_123
myname50   _temp   j     a23b9      retVal

Keywords

The following table lists the reserved words in C. These reserved words cannot be used as constant names, variable names, or other identifier names.

##autoelselongswitch##break casecharconst##continuegotosizeof volatiledefaultifstaticwhiledointstruct_Packed

enum	register	typedef
extern	return	union
#float	short	unsigned
for	signed	void
			##double
			Spaces in C Lines containing only whitespace are called blank lines, may be commented, and will be completely ignored by the C compiler. In C, whitespace is used to describe whitespace, tabs, newlines, and comments. Whitespace separates parts of a statement, allowing the compiler to identify where one element in the statement (such as an int) ends and the next element begins. So, in the following statement: int age; Here, there must be at least one space character (usually a whitespace character) between int and age so that the compiler can distinguish them. On the other hand, in the following statement: fruit = apples + oranges;   // 获取水果的总数 The space character between fruit and =, or = and apples is not required, but you can add some spaces if needed to enhance readability. ← C program structure C data type → submit php.cn HomeCourseArticleQ&ADictionaryManualDownloadsearch APPDownload