argument to number C++

#include <iostream>
#include <sstream>

int main() {
    std::string input;
    std::cout << "Enter a number: ";
    std::cin >> input;

    std::istringstream iss(input);
    int number;
    iss >> number;

    if (iss.fail()) {
        std::cout << "Invalid input! Please enter a valid number.";
    } else {
        std::cout << "The number entered is: " << number;
    }

    return 0;
}

Explanation:

1. #include <iostream>: Includes the input/output stream library for basic input and output operations.

2. #include <sstream>: Includes the string stream library for handling string-based input/output operations.

3. int main() { }: The main function where the program execution begins.

4. std::string input;: Declares a string variable named input to store the user's input.

5. std::cout << "Enter a number: ";: Outputs a message asking the user to enter a number.

6. std::cin >> input;: Reads user input from the standard input (keyboard) and stores it in the input variable.

7. std::istringstream iss(input);: Creates a string stream object iss and initializes it with the content of the input string.

8. int number;: Declares an integer variable named number to store the converted number.

9. iss >> number;: Attempts to extract an integer value from the string stream iss and store it in the number variable.

10. if (iss.fail()) { } else { }: Checks if the extraction was successful.

11. std::cout << "Invalid input! Please enter a valid number.";: If the extraction fails (i.e., invalid input), outputs an error message.

12. std::cout << "The number entered is: " << number;: If the extraction is successful, outputs the entered number.

13. return 0;: Indicates successful program execution and terminates the main function.