C Basic syntax

C Basic syntax

We've seen the basic structure of the C program, which will help us understand the other basic building blocks of the C language.

Tokens for C (Tokens)

The C program consists of a variety of tokens, which can be keywords, identifiers, constants, string values, or a symbol. For example, the following C statement includes five tokens:

printf("Hello, W3Cschool! \n");

The five tokens are:

printf    // 标识符
(    // 符号
"Hello, W3Cschool! \n"    // 字符串值
)    // 符号
;    // 分号是语句结束符

A sign;

In a C program, a sign is the statement end character. T hat is, each statement must end with a sign. It indicates the end of a logical entity.

For example, here are two different statements:

printf("Hello, W3Cschool! \n");
return 0;

Comments

Comments are like help text in a C program, and they are ignored by the compiler. They start /* end with the */ as follows:

// 单行注释

/* 
   多行注释
   多行注释
   多行注释
   */

• // known as line-level comments because only one line can be commented
• /* */ comment, also known as a quick-level comment, and a comment in this format can be one or more lines.

Error demo:

//我是单行注释//的错误演示
char a ='//A';

Identifier

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

Punctuation characters, such as , $, and %, @ $ C % C is a case-sensitive programming language. T herefore, in C, Manpower and manpower are two different identifiers. Here are a few valid identifiers:

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.

Spaces in C

A line that contains only spaces, called a blank line, may be annotated and ignored entirely by the C compiler.

In C, spaces are used to describe blanks, tabs, line breaks, and comments. S paces separate parts of a statement, allowing the compiler to identify where int ends and where the next element begins. Therefore, in the following statement:

int age;

Here, there must be age one space character (usually a blank 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

fruit = fruit and , apples are not required, but for greater readability, you can add some spaces as needed. =