In the C programming language, tokens are the basic units of syntax that the compiler uses to understand the code. Tokens are classified into six categories: identifiers, keywords, constants, operators, punctuators, and special symbols.
Identifiers: An identifier is a sequence of characters used to name a variable, function, or any other user-defined item. Identifiers must start with a letter (a-z or A-Z) or an underscore (_), and can be followed by any combination of letters, digits, or underscores. Identifiers are case-sensitive. Examples of identifiers are
sum,avg, andmy_var.Keywords: Keywords are reserved words in the C language that have a special meaning and cannot be used as identifiers. Examples of keywords include
if,else,for,while,switch,int,char,float,double,return, andstruct.Constants: Constants are fixed values that cannot be changed during program execution. There are two types of constants in C: integer constants and floating-point constants. Integer constants can be decimal, octal, or hexadecimal. Floating-point constants can be represented in decimal or exponential form. Examples of constants are
123,0x7F,3.14, and6.02e23.Operators: Operators are symbols that perform operations on one or more operands. C has several types of operators, including arithmetic, logical, relational, and bitwise operators. Examples of operators are
+,-,*,/,%,&&,||,==,!=,>,<,&,|, and~.Punctuators: Punctuators are symbols that are used to separate or group elements of a C program. Examples of punctuators are
;,,,(,),{, and}.Special symbols: Special symbols are characters that have a special meaning in C, such as the backslash () used to escape characters, and the apostrophe (') used to denote single-character constants. Examples of special symbols are
\n,\t,\', and\".
In summary, C uses a variety of tokens to construct the language's syntax. By understanding the different types of tokens and their usage, programmers can write C programs that are clear, concise, and easy to understand.