将VB.Net代码转换为C#时出现逻辑错误

Question

我有这个VB.Net代码:

Dim t as String = "111100111000011110111110010111101001100001100011101000001010011100110110100110100000101001110010011001101"
Dim i as Integer
If (t.Length Mod 8) <> 0 Then
    For i = 1 To 8 - (t.Length Mod 8)
        t = "0" + t
    Next
End If

当我将它转换为C#时,它变为:

string t = "111100111000011110111110010111101001100001100011101000001010011100110110100110100000101001110010011001101";

int i = 0;
if ((t.Length % 8) != 0)
{
    for (i = 1; i <= (8 - (t.Length%8)); i++)
    {
        t = "0" + t;
    }
}

问题是两个代码的结果不一样.因此VB.net代码执行7次,C#代码执行4次.

请告诉我是什么问题!

Answer 1

ForVB中的边界是预先计算的,并且在执行循环时不会改变.因此t.Length Mod 8计算一次然后使用该值.

在C#中,每次都会评估条件,因为您不断更改t,t.Length Mod 8每次都会给出新的值.

此外,因为字符串在.NET中是不可变的,所以您的代码最多可生成7个副本t.你应该这样做:

Dim diff As Integer = t.Length Mod 8

If diff <> 0 Then
    t = New String("0"c, 8 - diff) & t
End If