Tokens in C++ are the smallest units of a program that have a meaning. They are the building blocks of C++ code. Here are the main types of tokens:
Keywords: These are reserved words in C++ that have specific meanings and cannot be used as identifiers. Examples include int, float, char, if, else, for, while, etc.
Identifiers: These are user-defined names given to variables, functions, constants, etc. They must start with a letter or underscore and can contain letters, digits, or underscores. Examples include age, name, calculate_area.
Operators: These are symbols used to perform operations on operands. Examples include +, -, *, /, %, =, ==, !=, <, >, <=, >=, &&, ||, !, etc.
Punctuators: These are symbols used to separate different parts of a C++ program. Examples include (), {}, [], ;, ,, #, etc.
Literals: These are constant values that can be directly used in a C++ program. Examples include 10, 3.14, 'A', "Hello", true, false.
Keywords are crucial in C++ as they define the structure and behavior of the program. They are used to declare data types, control the flow of execution, define functions, and perform other essential tasks.
Identifiers are used to give meaningful names to variables, functions, and other entities in the program. They make the code more readable and easier to understand. When choosing identifiers, it's important to follow naming conventions to improve code maintainability.
Here's a simple example to illustrate the use of tokens:
int main() {
int age = 25; // 'int' is a keyword, 'age' is an identifier, '=' is an operator, '25' is a literal
char name = 'A'; // 'char' is a keyword, 'name' is an identifier, '=' is an operator, 'A' is a literal
cout << "Age: " << age << endl; // 'cout' is an identifier, '<<' is an operator, 'endl' is an identifier
cout << "Name: " << name << endl;
return 0;
}
In this code, int, char, main, age, name, cout, and endl are all identifiers. The operators =, <<, and << are used to perform assignments and output operations. The literals 25 and 'A' represent constant values.
By understanding tokens, keywords, and identifiers, you can lay a strong foundation for writing well-structured and efficient C++ programs.
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