How to only accept character on c-CodePudding

In my program, when the user is prompted for an employee's name, the system prompts him to re-enter his name if he enters a number or only a space. How do I put a requirement decision in parentheses in a while loop, here's my code.

std::string NAME;
std::cout << "Please enter the name: " << std::endl;
  std::cin >> NAME;
  while (NAME.length() == 0) {
    std::cout << "Your input is not correct. Please re-enter your name" << std::endl;
    std::cin >> NAME;
  }

I'm only going to restrict the input to not being empty, but I don't know how to get the user to only allow characters to enter.

Thank you all.

CodePudding user response：

You can use std::all_of on the string defined in algorithm header file. It should be used with appropriate predicate (isalpha for your case defined in cctype header file). Try this:

#include <iostream>
#include <algorithm>
#include <cctype>


int main()
{
    std::string NAME;
    std::cout << "Please enter the name: " << std::endl;

    while (std::getline(std::cin, NAME)) {
        if (NAME.length() == 0)
        {
            std::cout << "Your input is not correct. Please re-enter your name" << std::endl;
        }

        // This will check if the NAME contains only characters.
        else if (std::all_of(NAME.begin(), NAME.end(), isalpha))
        {
            break;
        }
        else {
            std::cout << "Only characters are allowed:" << std::endl;
        }
    }
}

CodePudding user response：

Every character has an ASCII code. Use an if condition to check if an input character falls between the ASCII codes for the English alphabets. ASCII Table. You can convert a character to its ASCII code by simply type-casting it as an integer.

Example: For a character array "ARR", having data: "apple"; doing the following will give you "97".

std::cout << (int)ARR[0] << std::endl;