C Basic Syntax

2       C Basic Syntax

Tokens in C 

A C program consists of various tokens and a token is either a keyword, an identifier, a constant, a string literal, or a symbol. 

For example, the following C statement consists of five tokens: 

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

Semicolons ;

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

Comments 

Comments are like helping text in your C program and they are ignored by the compiler. 

They start with /* and terminates with the characters */ as shown below:

/* my first program in C */

note:You cannot have comments within comments and they do not occur within a string or character literals.

Identifiers

 A C 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).

C does not allow punctuation characters such as @, $, and % within identifiers. C is a case sensitive programming language. 

Thus, Manpower and manpower are two different identifiers in C. Here are some examples of acceptable identifiers: 

mohd     zara     abc     move_name     a_123     myname50 _temp     j     a23b9     retVal

Keywords

The following list shows the reserved words in C. These reserved words may not be used as constant or variable or any other identifier names. 

auto     else     Long     switch     break     enum     register     typedef     case     extern     return     union char     float     short     unsigned     const     for     signed     void     continue     goto     sizeof     volatile default     if     static     while     do     int     struct     packed     double

Whitespace in C

 A line containing only whitespace, possibly with a comment, is known as a blank line, and a C compiler totally ignores it.

 Whitespace is the term used in C to describe blanks, tabs, newline characters and comments. Whitespace separates 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: 

int age;

note1: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.

note2: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.