Mid是Vb中的一個字符串函數(shù)，作用是從一個字符串中截取出指定數(shù)量的字符。這個函數(shù)的3個參數(shù)在VB中的Length參數(shù)可以省略。

當(dāng)Start（start_num）參數(shù)小于1時，函數(shù)返回一個錯誤當(dāng)Start參數(shù)值大于String（text）參數(shù)長度時，返回一空字符串若從Start參數(shù)起截取長度超出字符串末尾，或Length參數(shù)被省略，則返回Start參數(shù)位置到字符串結(jié)尾的所有字符。

VB語法：

1、Mid(String As Variant， Start As Long， [Length As Variant]) As Variant

2、Mid$(String As String， Start As Long， [Length As Variant]) As String