这个循环怎么了? [英] Whats wrong with this loop?

问题描述

Public Class Form1
    Dim str() As String
    Dim x As Integer
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        For x = 0 To 5
            str(x) = " D"
        Next
    End Sub
End Class

我以前可能发誓要通过一个循环将字符串添加到数组中，而现在却出错了.

I could have sworn to adding strings to an array in the past through a loop worked and now it just errors out.

推荐答案

您尚未定义数组大小. br/> 您已声明一个未初始化的数组，从而导致错误.

使用

You have not defined the array size.
You have declared an array that is then not initialized thus causing errors.

Use

Dim str(4) As String

，您应该没事.

字符串是不可变的，请使用StringBuilder

从文档复制:
字符串是Unicode字符的顺序集合，通常用于表示文本，而String是表示字符串的System.Char对象的顺序集合. String的值是顺序集合的内容，并且值是不可变的.

字符串被称为不可变的，因为一旦创建它的值就无法对其进行修改.看似修改String的方法实际上返回一个包含修改的新String.如果有必要修改类似字符串的对象的实际内容，请使用System.Text.StringBuilder类.

问候
Espen Harlinn

String is immutable, use StringBuilder

Copied from documentation:
A string is a sequential collection of Unicode characters, typically used to represent text, while a String is a sequential collection of System.Char objects that represents a string. The value of the String is the content of the sequential collection, and the value is immutable.

A String is called immutable because its value cannot be modified once it has been created. Methods that appear to modify a String actually return a new String containing the modification. If it is necessary to modify the actual contents of a string-like object, use the System.Text.StringBuilder class.


Regards
Espen Harlinn

另一种方法是:

Another way to do is:

Dim MyList as new list(of string)

For X = 0 to 5
    MyList.add " D"
Next

''Now you can just use MyList.ToArray()

祝你好运！ :thumbsup:

埃里克.

Good luck! :thumbsup:

Erik.

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