vb.net 中的 Strings类字符串操作的所有函数及其功能和详细代码每行上面注释

在 VB.NET 中，Strings 类提供了许多用于字符串操作的函数，以下是其中一些常用函数及其功能和详细代码：

1. Len(str As String) As Integer

功能：返回字符串的长度。

详细代码：

Dim str As String = "hello world"
Dim len As Integer = Len(str) ' 获取字符串长度

2. Mid(str As String, start As Integer, [length As Integer]) As String

功能：返回从指定位置开始的指定长度的子字符串。

详细代码：

Dim str As String = "hello world"
Dim subStr As String = Mid(str, 1, 5) ' 获取从字符串第一个字符开始的前5个字符

3. InStr([start As Integer, ]string1 As String, string2 As String[, compare As CompareMethod = CompareMethod.Binary]) As Integer

功能：返回一个字符串在另一个字符串中第一次出现的位置。

详细代码：

Dim str As String = "hello world"
Dim index As Integer = InStr(str, "world") ' 获取子字符串 "world" 在原字符串中的位置

4. Replace(expression As String, find As String, replacement As String[, start As Integer = 1[, count As Integer = -1[, compare As CompareMethod = CompareMethod.Binary]]]) As String

功能：替换字符串中指定的子字符串。

详细代码：

Dim str As String = "hello world"
Dim newStr As String = Replace(str, "world", "vb.net") ' 将子字符串 "world" 替换为 "vb.net"

5. Trim([string]) As String

功能：去除字符串两端的空格。

详细代码：

Dim str As String = " hello world "
Dim newStr As String = Trim(str) ' 去除字符串两端的空格

6. LCase(string) As String

功能：将字符串转换为小写。

详细代码：

Dim str As String = "Hello World"
Dim newStr As String = LCase(str) ' 将字符串转换为小写

7. UCase(string) As String

功能：将字符串转换为大写。

详细代码：

Dim str As String = "Hello World"
Dim newStr As String = UCase(str) ' 将字符串转换为大写

8. Str(str As Object) As String

功能：将数字或其他数据类型转换为字符串。

详细代码：

Dim num As Integer = 123
Dim str As String = Str(num) ' 将数字 123 转换为字符串