VB.NET生成随机串或随机数字的方法总结

本文一共介绍了5种生成随机数方式，具体如下：

第一种：转载的方法

public enum stringtype
    allstring = 1    '大小写字母
    allnumic = 2    '数字
    str_num = 3    '大小写字母+数字
    str_upper = 4    '大写字母
    str_lower = 5 '大写字母  
  end enum
  function generaterandom(byval length as integer, byval s as stringtype) as string
    dim strtemp as string = ""
    dim constant() as string = nothing
    select case s
      case stringtype.allnumic
        strtemp = "0,1,2,3,4,5,6,7,8,9"
        constant = strtemp.split(",")
      case stringtype.allstring
        strtemp = "a,b,c,d,e,f,g,h,i,j,k,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,d,g,h,i,j,k,l,m,n,p,q,r,s,t,u,v,w,x,x,y,z"
        constant = strtemp.split(",")
      case stringtype.str_lower
        strtemp = "a,b,c,d,e,f,g,h,i,j,k,m,n,o,p,q,r,s,t,u,v,w,x,y,z"
        constant = strtemp.split(",")
      case stringtype.str_num
        strtemp = "a,b,c,d,e,f,g,h,i,j,k,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,d,g,h,i,j,k,l,m,n,p,q,r,s,t,u,v,w,x,x,y,z,0,1,2,3,4,5,6,7,8,9"
        constant = strtemp.split(",")
      case stringtype.str_upper
        strtemp = "a,b,c,e,f,d,g,h,i,j,k,l,m,n,p,q,r,s,t,u,v,w,x,y,z"
        constant = strtemp.split(",")
    end select
    dim newrandom as system.text.stringbuilder = new system.text.stringbuilder(length)
    dim rd as random = new random()
    dim i as integer
    for i = 0 to length - 1 step i + 1
      newrandom.append(constant(rd.next(constant.length - 1)))
    next
    return newrandom.tostring()
  end function

第二种：网上查找

public function getoauthnonce() as string ' 得到随机值
    dim result as string = system.guid.newguid().tostring()
    result = result.replace("-", "")
    return result.substring(0, 10)
  end function

public function randcode(byval n as integer) as string
    dim arrchar as char() = new char() {"a"c, "b"c, "d"c, "c"c, "e"c, "f"c, _
                      "g"c, "h"c, "i"c, "j"c, "k"c, "l"c, _
                      "m"c, "n"c, "p"c, "r"c, "q"c, "s"c, _
                      "t"c, "u"c, "v"c, "w"c, "z"c, "y"c, _
                      "x"c, "0"c, "1"c, "2"c, "3"c, "4"c, _
                      "5"c, "6"c, "7"c, "8"c, "9"c, "a"c, _
                      "b"c, "c"c, "d"c, "e"c, "f"c, "g"c, _
                      "h"c, "i"c, "j"c, "k"c, "l"c, "m"c, _
                      "n"c, "q"c, "p"c, "r"c, "t"c, "s"c, _
                      "v"c, "u"c, "w"c, "x"c, "y"c, "z"c}
    dim num as new stringbuilder()
    dim rnd as new random(datetime.now.millisecond)
    for i as integer = 0 to n - 1
      num.append(arrchar(rnd.[next](0, arrchar.length)).tostring())
    next
    return num.tostring()
  end function

第三种：原来是c#转换

public function randcode(byval n as integer) as string
    dim arrchar as char() = new char() {"a"c, "b"c, "d"c, "c"c, "e"c, "f"c, _
                      "g"c, "h"c, "i"c, "j"c, "k"c, "l"c, _
                      "m"c, "n"c, "p"c, "r"c, "q"c, "s"c, _
                      "t"c, "u"c, "v"c, "w"c, "z"c, "y"c, _
                      "x"c, "0"c, "1"c, "2"c, "3"c, "4"c, _
                      "5"c, "6"c, "7"c, "8"c, "9"c, "a"c, _
                      "b"c, "c"c, "d"c, "e"c, "f"c, "g"c, _
                      "h"c, "i"c, "j"c, "k"c, "l"c, "m"c, _
                      "n"c, "q"c, "p"c, "r"c, "t"c, "s"c, _
                      "v"c, "u"c, "w"c, "x"c, "y"c, "z"c}
    dim num as new stringbuilder()
    dim rnd as new random(datetime.now.millisecond)
    for i as integer = 0 to n - 1
      num.append(arrchar(rnd.[next](0, arrchar.length)).tostring())
    next
    return num.tostring()
  end function

第四种：利用vb6转换

function makerand(byval maxlen as integer) as string '生成签名时用随机串
    dim strnewpass as string = vbnullstring
    dim lower as long
    dim whatsnext as long
    dim upper as long
    dim intcounter as long
    randomize()
    for intcounter = 1 to maxlen
      whatsnext = int((1 - 0 + 1) * rnd() + 0)
      if whatsnext = 0 then
        upper = 122
        lower = 100
      else
        upper = 57
        lower = 48
      end if
      strnewpass = strnewpass & chr(int((upper - lower + 1) * rnd() + lower))
    next
    makerand = strnewpass
  end function

第五种：直接用vb.net函数

  dim rand as random = new system.random(10)‘这里10就代表是10为
   debug.print(rand.next().tostring)

原文链接：http://blog.csdn.net/lcp58006478/article/details/8958460

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