Basic Syntax in C Programming | Programming and Data Structures - Computer Science Engineering (CSE) PDF Download

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. 

Example: The following C statement consists of five tokens.

printf("Hello, World! ");

The individual tokens are:

printf
(
"Hello, World! 
"
)
;

Question for Basic Syntax in C Programming

Try yourself:The number of tokens in the following C statement. 
printf("i = %d, &i = %x", i, &i);is

• A.

  3  
• B.

  26  
• C.

  10    
• D.

  21

Explanation

The smallest individual units are known as C Tokens. The keywords, identifiers, constants, string literals, and operators described in this section are examples of tokens. Punctuation characters such as brackets ([ ]), braces ({ }), parentheses ( ( ) ), and commas (,) are also tokens.
Example:
printf("Hello, World! \n");
The tokens for the above statement are:
1) printf
2) (
3) "Hello, World! \n"
4) )
5) ;
So there are 5 tokens
printf("i = %d, &i = %x", i, &i);
10 Tokens are:
1) printf
2) (
3) "i = %d, &i = %x"
4) ,
5) i
6) ,
7) &
8) i
9) )
10);

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➢ Semicolons

• In a 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.

Given below are two different statements:

printf("Hello, World! 
");
return 0;

➢ Comments

• Comments are like helping text in your C program and they are ignored by the compiler. 
• They start with /* and terminate with the characters */ as shown below:

/* my first program in C */

• 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, 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 constants or variables or any other identifier names.

➢ 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;

• 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 to increase readability.