dim函數(shù)的第三個(gè)參數(shù)，也就是截取字符的長(zhǎng)度，我在設(shè)置這個(gè)的時(shí)候，出了些問(wèn)題,提示無(wú)效的過(guò)程調(diào)用或參數(shù),本文詳細(xì)介紹如何解決

dim函數(shù)的第三個(gè)參數(shù)，也就是截取字符的長(zhǎng)度，我在設(shè)置這個(gè)的時(shí)候，出了些問(wèn)題:response.write mid(up_address,a(i),a(i+1)-1) & “<br />”像我上面這樣寫(xiě)的時(shí)候，它就會(huì)報(bào)錯(cuò)，提示無(wú)效的過(guò)程調(diào)用或參數(shù),

response.write mid(up_address,a(i),a(i+1)+1) & “<br />”但是當(dāng)我把其中的a(i+1)-1改為a(i+1)+1時(shí)，就能執(zhí)行了,a(i+1)對(duì)應(yīng)的值是11，可為什么只能減不能加呢?全部代碼如下:

VB code:

代碼如下:

dim a(),up_address

up_address = "aaa djaldk adflj adafadfasdfa afd ad"

redim a(len(up_address))

a(0) = instr(up_address," ")

response.write a(0) & "<br />"

if a(0)<>0 then

for i=0 to len(up_address)-1

a(i+1) = instr(a(i)+1,up_address," ")

response.write mid(up_address,a(i),a(i+1)-1) & "<br />"

if a(i+1)=0 then

exit for

end if

response.write a(i+1) & "<br />"

next

end if如上代碼，我是想把字符串按空格分解出來(lái)，但是mid的第三個(gè)參數(shù)那出了點(diǎn)問(wèn)題，我本來(lái)是想這樣截取的：

VB code：

代碼如下:

mid(up_address,a(i),a(i+1)-a(i)-1)

‘a(chǎn)(i)是空格的位置

‘a(chǎn)(i+1)是下一個(gè)空格的位置

‘a(chǎn)(i+1)-a(i)-1是兩個(gè)空格直間的字符長(zhǎng)度

現(xiàn)在的問(wèn)題是，經(jīng)測(cè)試，mid的第三個(gè)參數(shù)那，無(wú)法使用減法，也就是說(shuō)，我可以寫(xiě)a(i+1)+，但不能寫(xiě)a(i+1)-，想了好久，我一直不明白問(wèn)題出在哪？應(yīng)該怎么來(lái)解決呢？

出現(xiàn)這個(gè)問(wèn)題是因?yàn)樯厦娴腗ID函數(shù)的第三個(gè)參數(shù)出現(xiàn)了負(fù)數(shù),下面是在網(wǎng)上找的測(cè)試的VBS代碼，原理一樣，如下的代碼：

VBScript code:

代碼如下:

dim a(),up_address

up_address = "aaa djaldk adflj adafadfasdfa afd ad"

MsgBox len(up_address) '36

redim a(len(up_address)) 'a(36)

a(0) = instr(up_address," ")

MsgBox a(0) 'a(0)=4

MsgBox a(0) & "<br />"

if a(0)<>0 then

for i=0 to len(up_address)-1

a(i+1) = instr(a(i)+1,up_address," ")

MsgBox a(i) &" "& (a(i+1)-1)‘這里的結(jié)果為34，-1，所以導(dǎo)致出錯(cuò)

MsgBox mid(up_address,a(i),a(i+1)-1) & "<br />"

if a(i+1)=0 then

exit for

end if

MsgBox a(i+1) & "<br />"

next

end if