//-下载文件要用到操作系统的API函数，下面是一个WINDOWS系统中的实现：---------------

#include <stdio.h>
#include <windows.h>
#include <wininet.h>
#define MAXBLOCKSIZE 1024
#pragma comment( lib, "wininet.lib" ) ;

void download(const char *Url,const char *save_as)/*将Url指向的地址的文件下载到save_as指向的本地文件*/
{
	byte Temp[MAXBLOCKSIZE];
	ULONG Number = 1;
	
	FILE *stream;
	HINTERNET hSession = InternetOpen((LPCWSTR)"RookIE/1.0", INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
	if (hSession != NULL)
	{
		HINTERNET handle2 = InternetOpenUrl(hSession, (LPCWSTR)Url, NULL, 0, INTERNET_FLAG_DONT_CACHE, 0);
		if (handle2 != NULL)
		{
			
			
			if( (stream = fopen( save_as, "wb" )) != NULL )
			{
				while (Number > 0)
				{
					InternetReadFile(handle2, Temp, MAXBLOCKSIZE - 1, &Number);
					
					fwrite(Temp, sizeof (char), Number , stream);
				}
				fclose( stream );
			}
			
			InternetCloseHandle(handle2);
			handle2 = NULL;
		}
		InternetCloseHandle(hSession);
		hSession = NULL;
	}
}

int main(int argc, char* argv[]){
	
	download("http://www.baidu.com/","c:\\index.html");/*调用示例，下载百度的首页到c:\index.html文件*/
	return 0;
}