Introduction to C++ | Keywords

C++ Keywords

In C++, keywords are reserved words that have a special meaning to the compiler. They are part of the syntax of the C++ language and cannot be used as identifiers (e.g., variable names, function names). C++ has a set of predefined keywords that form the foundation of the language's structure.

Common C++ Keywords

C++ has many keywords, and here are some of the most commonly used:

1. Data Types

• int: Defines an integer variable.
• float: Defines a floating-point variable (single precision).
• double: Defines a floating-point variable (double precision).
• char: Defines a character variable.
• bool: Defines a boolean variable, which can be either true or false.

2. Control Flow

• if: Conditional statement used for decision-making.
• else: Specifies the block of code to execute if the condition is false.
• switch: A control statement for multiple conditions based on a single expression.
• case: Defines a block of code for each value in a switch statement.
• break: Exits a loop or switch statement.
• continue: Skips the current iteration of a loop and proceeds to the next iteration.

3. Functions

• return: Exits a function and optionally returns a value.
• void: Specifies that a function does not return a value.

4. Object-Oriented Programming (OOP)

• class: Defines a class in object-oriented programming.
• private: Specifies private members of a class (not accessible outside the class).
• public: Specifies public members of a class (accessible outside the class).
• protected: Specifies protected members of a class (accessible within the class and derived classes).
• this: Refers to the current instance of the class.

5. Memory Management

• new: Allocates memory dynamically on the heap.
• delete: Deallocates dynamically allocated memory.

Code Example: Using Keywords in C++

Here's an example that demonstrates the use of various C++ keywords.

                #include <iostream>
                using namespace std;
        
                // Function definition
                void displayMessage() {
                    cout << "Hello, this is a simple C++ program!" << endl;
                }
        
                int main() {
                    int num = 10;
                    bool isActive = true;
        
                    // Conditional statement using 'if' and 'else'
                    if (isActive) {
                        cout << "The program is active." << endl;
                    } else {
                        cout << "The program is inactive." << endl;
                    }
        
                    // Calling the function 'displayMessage'
                    displayMessage();
        
                    // Returning from the function
                    return 0;
                }
                    

Output

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