c++ - 如何验证用户将字符串输入到 std::cin 中？

Question

students[#] 是一个结构数组，students[#].name 是结构中的一个字符串，我想确保当用户输入验证为字符串的名称。

谁能告诉我完成这项工作的(简单的？)方法吗？

我已经尝试了以下无济于事。

        bool checkString(const char *str)
        {
            bool isLetters = true;

            while (*str != '\0')
            {
                if (*str < '65' || *str > '122')
                {
                   //checking to see if it's over or below ASCII alpha characters
                    isLetters = false;
                }

                if (*str < '97' && *str > '90')
                {
                     // checking to see if it's between capital and 
                     //lowercase alpha char's
                    isLetters = false;
                }

                ++str;
            }

            return isLetters;
        }

        main
        {
        //...
                for (int i = 0; i < numStudents; ++i)
                {
                    valid = true;
                    do
                    {
                        valid = true;
                        cout << "Enter NAME for student #" << i + 1 << ":" << endl;
                        cin >> students[i].name;
                        if (cin.fail() || !checkString(students[i].name.c_str()))
                            // tried to see if i could convert it to a c-style 
                            //string to check char by char
                        {
                            cin.clear();
                            cin.ignore();
                            cout << "Please enter a valid input." << endl;
                            valid = false;
                        }
                    } while (!valid);
        //...
        return 0;
        }

        `

Answer 1

ASCII 码是整数，不要放在引号中。

bool checkString(const char *str)
{
    bool isLetters = true;
    while (*str != '\0')
    {
        if (*str < 65 || *str > 122)
        {
           //checking to see if it's over or below ASCII alpha characters
            isLetters = false;
        }

        if (*str < 97 && *str > 90)
        {
             // checking to see if it's between capital and 
             //lowercase alpha char's
            isLetters = false;
        }
        ++str;
    }
    return isLetters;
}

虽然你仍然在努力，函数 isalpha 是为这个任务设计的

#include <cctype>

bool checkString(const char *str)
{
    bool isLetters = true;
    while (*str != '\0')
    {
        if (!isalpha(*str)))
            isLetters = false;
        ++str;
    }
    return isLetters;
}

然后发现不是信就可以马上返回，再查也没用

#include <cctype>

bool checkString(const char *str)
{
    while (*str != '\0')
    {
        if (!isalpha(*str)))
            return false;
        ++str;
    }
    return true;
}