c# - 如何在 foreach 循环中为 char 变量赋值？ C#

Question

我想做的是这样的:

StringBuilder sb = new StringBuilder();

foreach(char ch in valor)
{
    if (ch == ',')
        ch = '.';
    else if (ch == '0' || ch == '1' || ch == '2' || ch == '3' || ch == '4' || ch == '5' || ch == '6' || ch == '7' || ch == '8' || ch == '9' || ch == ',')
    {
        sb.Append(ch);
    }
}

我想要的是，如果该字符是逗号，则将其设为点。但我收到以下错误

it is not possible to assign value to 'ch' because it is a foreach interaction variable

Answer 1

为什么不在两个 if 分支中追加？

foreach(char ch in valor)
{
    if (ch == ',')
    {
        sb.Append('.');
    }
    else if (ch == '0' || ch == '1' || ch == '2' || ch == '3' || ch == '4' || ch == '5' || ch == '6' || ch == '7' || ch == '8' || ch == '9')
    {
        sb.Append(ch);
    }
}