Tokens in C language are the smallest individual units of a program, such as keywords, identifiers, constants, operators, and special symbols. Here’s an explanation of each type of token with examples:
- Keywords:
- Keywords are reserved words that have predefined meanings in C language.
- Example:
int,if,else,for,while,return,void,struct, etc.
- Identifiers:
- Identifiers are names given to various program elements such as variables, functions, arrays, etc.
- Rules for identifiers: They must begin with a letter (uppercase or lowercase) or an underscore (_), followed by letters, digits, or underscores.
- Example:
sum,i,MAX_SIZE,calculateArea,first_name, etc.
- Constants:
- Constants are fixed values that do not change during program execution.
- Types of constants include integer constants, character constants, floating-point constants, and string constants.
- Example integer constant:
10,-20,0xFF(hexadecimal),077(octal), etc. - Example character constant:
'A','b','7','%', etc. - Example floating-point constant:
3.14,-0.0012,2.0E-5, etc. - Example string constant:
"Hello","123","C programming", etc.
- Operators:
- Operators perform operations on operands.
- Types of operators include arithmetic operators, relational operators, logical operators, assignment operators, etc.
- Example arithmetic operators:
+,-,*,/,%. - Example relational operators:
==,!=,<,>,<=,>=. - Example logical operators:
&&(AND),||(OR),!(NOT). - Example assignment operators:
=,+=,-=etc.
- Special Symbols:
- Special symbols include punctuation marks and other symbols used in C syntax.
- Example:
;(semicolon),,(comma),{}(curly braces),()(parentheses),[](square brackets),.(dot),->(arrow), etc.
- Whitespace:
- Whitespace includes spaces, tabs, and newlines.
- Whitespace is used to separate tokens but is otherwise ignored by the compiler.
- Example: Spaces between keywords, identifiers, operators, etc.
Example:
#include <stdio.h>
int main() {
int num1 = 10;
int num2 = 20;
int sum;
sum = num1 + num2;
printf("The sum is: %d\n", sum);
return 0;
}
In this example:
- Keywords:
int,return,void. - Identifiers:
main,num1,num2,sum. - Constants:
10,20,0. - Operators:
=,+. - Special Symbols:
{,},=,;,(),,,"\n". - Whitespace: Spaces, newlines.