@echo off&setlocal enabledelayedexpansion
for /f "delims=" %%a in (a.txt) do (
     for %%i in (%%a) do (
          set "var=%%i"
          if "!var:~,2!" equ "5-" (
             if not defined max set "max=!var:~2!" 
             if !var:~2! geq !max! set "max=!var:~2!"   
          )
     )
)
echo %max%&pause>nul

@echo off&setlocal enabledelayedexpansion
for /f "delims=" %%a in (a.txt) do (
     for %%b in (%%a) do (
          set "var=%%b"
          if "!var:~,2!" equ "5-" (
             if not defined max set "max=!var:~2!"
             for /f "tokens=1* delims=." %%c in ("!max!") do set "max1=%%c"&set "max2=%%d"
             for /f "tokens=1* delims=." %%e in ("!var:~2!") do (
                 if %%e gtr !max1! (
                    set "max=!var:~2!"
                    ) else (
                    if %%e equ !max1! if %%d gtr !max2! set "max=!var:~2!"
　　　　　　　　 )
             )
          )
     )
)
echo %max%&pause>nul

set fso=createobject("scripting.filesystemobject")
set f=fso.opentextfile("a.txt",1)

while f.atendofstream <> true
  r=r&split(split(f.readline,"5-")(1))(0)&" " '提取所有5-后的数字
wend
r=split(r)                                    '转换为数组
n=ubound(r)                                   '确定数组最大下标
for i=0 to n-1                                '转换数值类型
        r(i)=cdbl(r(i))
next
quicksort r,0,n
msgbox r(n-1)

'快速排序：
'划分：
function partition(r,l,h)
        dim i,j,t
        i=l
        j=h
        t=r(i)'初始化，t为基准
        do 
                while r(j)>=t and i<j
                        j=j-1'从右向左扫描，查找第1个小于t的数
                wend
                if i<j then 
                        r(i)=r(j)'交换r(i)和r(j)
                        i=i+1
                end if
                while r(i)<=t and i<j
                        i=i+1'从左向右扫描，查找第1个大于t的数
                wend
                if i<j then 
                        r(j)=r(i)'交换r(i)和r(j)
                        j=j-1
                end if                
        loop while i<>j
        r(i)=t'基准t已被最后定位
        partition=i
end function
        '排序：
sub quicksort(r,s1,t1)
        dim i
        if s1<t1 then'只有一个数或无数时无须排序
                i=partition(r,s1,t1)'对r(s1)到r(t1)做划分
                quicksort r,s1,i-1'递归处理左区间
                quicksort r,i+1,t1'递归处理右区间
        end if
end sub

gawk "{for (i=1;i<=NF;i++) { if($i~/^5-[0-9]/){ split($i,a,/-/); if(a[2]>max) max=a[2]; }}} END{print max}" your_file

gawk "{for (i=1;i<=NF;i++) { if($i~/^5-[0-9]/){ split($i,a,/-/); if(a[2]>max) max=a[2]; }}} END{print max}" "a.txt"

gawk "{for (i=1;i<=NF;i++) { if($i~/^5-[0-9]/){ split($i,a,/-/); if(a[2]>max) max=a[2]; }}} END{print max}" "a.txt" > %temp%\tmp.p
set /p max=<%temp%\tmp.p
echo max 的值为 [%max%].