Return null的char值

Question

这是我的代码；

public void Dönüştür()
{
    int TextboxLength = TextBox.MaxLength;
    string LowerText = TextBox.Text.ToLower();
    var AllCharacters = "";

    for (int i = 0; i < TextboxLength; i++)
    {
        char Characters = char.Parse(LowerText);
        switch (Characters)
        {
            case '0': AllCharacters += "0"; break;
            case '1': AllCharacters += "1"; break;
            case '2': AllCharacters += "2"; break;
            case '3': AllCharacters += "3"; break;
            case '4': AllCharacters += "4"; break;
            case '5': AllCharacters += "5"; break;
            case '6': AllCharacters += "6"; break;
            case '7': AllCharacters += "7"; break;
            case '8': AllCharacters += "8"; break;
            case '9': AllCharacters += "9"; break;

            case ' ': case '+': case '-': case '_': AllCharacters += "0"; break;
            case ':': case ';': case '=': case ',': case '.': AllCharacters += "1"; break;
            case 'a': case 'b': case 'c': case 'ç': AllCharacters += "2"; break;
            case 'd': case 'e': case 'f': AllCharacters += "3"; break;
            case 'g': case 'ğ': case 'h': case 'ı': case 'i': AllCharacters += "4"; break;
            case 'j': case 'k': case 'l': AllCharacters += "5"; break;
            case 'm': case 'n': case 'o': case 'ö': AllCharacters += "6"; break;
            case 'p': case 'r': case 's': case 'ş': AllCharacters += "7"; break;
            case 't': case 'u': case 'ü': AllCharacters += "8"; break;
            case 'v': case 'y': case 'z': case 'x': case 'w': AllCharacters += "9"; break;
        }

    }
    MessageBox.Show(TextBox.MaxLength.ToString(), "TextBox MaxLength:");
    MessageBox.Show(AllCharacters.ToString(), "AllCharacters value:");
}

我想将数字转换为字母。 char 值，但它似乎是空的。

如果选中，则填充 TextBox，但 for 循环不起作用。原因可能是0个TextBox的字符数但是TextBox被填充了

问题出在哪里，我哪里出错了？

Answer 1

您正在循环 TextBox.MaxLength 指定的次数，该次数为零，因此根本不会循环。您是要按 TextBox.Text.Length 循环吗？

MaxLength 属性，如果设置为大于零，则限制可以输入到文本框中的字符数。

    for (int i = 0; i < TextBox.Text.Length; i++)
    {
         char Characters = LowerText[i];
         ...
    }

Return null的char值

Return the char value of null

c#

char

maxlength

letters-and-numbers