checking if a string has only letters cpp

To check if a string in C++ contains only letters, you can use the isalpha() function from the <cctype> library. Here are the steps to perform this check:

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

#include <cctype>

1. Declare a string variable that you want to check:

std::string str = "HelloWorld";

1. Use a loop to iterate through each character of the string:

for (char c : str) {
    // Perform the check for each character
}

1. Inside the loop, use the isalpha() function to check if the current character is a letter:

for (char c : str) {
    if (!isalpha(c)) {
        // Character is not a letter
        // Handle the case when the string contains non-letter characters
    }
}

1. If the isalpha() function returns false for any character, it means that the string contains a non-letter character. You can handle this case accordingly.

2. If the loop completes without encountering any non-letter characters, it means that the string contains only letters.

Here's an example that puts the above steps together:

#include <iostream>
#include <cctype>
#include <string>

int main() {
    std::string str = "HelloWorld";

    for (char c : str) {
        if (!isalpha(c)) {
            std::cout << "The string contains non-letter characters." << std::endl;
            return 0;
        }
    }

    std::cout << "The string contains only letters." << std::endl;

    return 0;
}

This example checks if the string "HelloWorld" contains only letters. If it does, it prints "The string contains only letters." Otherwise, it prints "The string contains non-letter characters."