use of alphanumeric function c++, check if alphabet or digit from string

To check if a character in a string is an alphabet or a digit in C++, you can use the isalpha() and isdigit() functions from the <cctype> library.

Here are the steps to check if a character is an alphabet or a digit in C++:

1. Include the <cctype> library at the beginning of your code.

cpp #include <cctype>

1. Get the input string from the user or initialize it.

cpp std::string input = "abc123";

1. Iterate through each character in the input string using a loop.

cpp for (char c : input) { // Check if the character is an alphabet or a digit }

1. Use the isalpha() function to check if the character is an alphabet. It returns a non-zero value (true) if the character is an alphabet, and 0 (false) otherwise.

cpp if (isalpha(c)) { // Character is an alphabet }

1. Use the isdigit() function to check if the character is a digit. It returns a non-zero value (true) if the character is a digit, and 0 (false) otherwise.

cpp if (isdigit(c)) { // Character is a digit }

1. Handle the cases where the character is neither an alphabet nor a digit.

cpp if (!isalpha(c) && !isdigit(c)) { // Character is neither an alphabet nor a digit }

1. Repeat the above steps for each character in the input string.

Here is an example that puts it all together:

#include <iostream>
#include <cctype>

int main() {
    std::string input = "abc123";

    for (char c : input) {
        if (isalpha(c)) {
            std::cout << c << " is an alphabet." << std::endl;
        }
        else if (isdigit(c)) {
            std::cout << c << " is a digit." << std::endl;
        }
        else {
            std::cout << c << " is neither an alphabet nor a digit." << std::endl;
        }
    }

    return 0;
}

This code will iterate through each character in the input string and check if it is an alphabet or a digit using the isalpha() and isdigit() functions. It will then print the appropriate message based on the result.