无法将属性或索引器'string.this [int]'分配给它-只读 [英] Property or indexer 'string.this[int]' cannot be assigned to -- it's read only

问题描述

我没有遇到问题-我试图做一个简单的动作:

I didn't get the problem - I was trying to do a simple action:

for(i = x.Length-1, j = 0 ; i >= 0 ; i--, j++)
{
    backx[j] = x[i];
}

两个都声明了:

String x;
String backx;

出什么问题了?它说标题中的错误...如果有问题-是否有另一种方法可以解决?结果(正如名称"backx"所暗示的)是backx将向后包含字符串X.P.S.x不为空-它包含另一个字符串的子字符串.

What is the problem ? It says the error in the title... If there is a problem - is there another way to do that? The result (As the name 'backx' hints) is that backx will contain the string X backwards. P.S. x is not empty - it contains a substring from another string.

推荐答案

字符串是不可变的:您可以在某个位置检索字符，但是不能直接将字符更改到新的字符.

Strings are immutable: you can retrieve the character at a certain position, but you cannot change the character to a new one directly.

相反，您必须使用更改来构建新的字符串.有几种方法可以做到这一点，但是 StringBuilder 的工作方式与您已有的方式类似:

Instead you'll have to build a new string with the change. There are several ways to do this, but StringBuilder does the job in a similar fashion to what you already have:

StringBuilder sb = new StringBuilder(backx);
sb[j] = x[i];
backx = sb.ToString();

如果您查看 string 面向公众的API，则会看到此索引器:

If you take a look at the string public facing API, you'll see this indexer:

public char this[int index] { get; }

这表明您可以获取"值，但是由于没有设置"可用，因此无法将值分配给该索引器.

This shows that you can "get" a value, but because no "set" is available, you cannot assign values to that indexer.

EDITx2:如果您正在寻找一种反转字符串的方法，则有几种不同的方法，但是这里有一个示例，说明了其工作原理:

EDITx2: If you're looking for a way to reverse a string, there are a few different ways, but here's one example with an explanation as to how it works: http://www.dotnetperls.com/reverse-string

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