帮帮忙，我错在哪里？（已经两天了！！！）(100分)

addrS:sockaddr_in;
....
Re:=recvfrom(fd,BufRecv^,1024,0,addrS,Pinteger(sizeof(addrS)));
....

[Error]Types of actual and formal var parameters must be identical

var
BufRecv:array[0..1023]of Char;
Len:Integer;
......
Len:=sizeof(addrS);
Re:=recvfrom(fd,BufRecv,1024,0,addrS,Len);

详见： http://www.delphibbs.com/delphibbs/dispq.asp?lid=263140

万分感谢！这个错误我自己是怎么也看不出来的！
但我很奇怪，为什么会错呢？（我试过，不用Pinteger也是错）
sizeof()本身求得的就是整型啊，为什么不能直接这么写呢！

int recvfrom (
SOCKET s,
char FAR* buf,
int len,
int flags,
struct sockaddr FAR* from,
int FAR* fromlen
);

Parameters

s
[in] A descriptor identifying a bound socket.

buf
[out] A buffer for the incoming data.

len
[in] The length of buf.

flags
[in] Specifies the way in which the call is made.

from
[out] An optional pointer to a buffer which will hold the source address upon return.

fromlen
[in/out] An optional pointer to the size of the from buffer.
~~~~~~~~~ 注意：此参数出了输入以外，还要输出，因此不能用常量代替

谢谢creation-zy的热心指点！