opencv 程序报错大家帮小弟我看看哪的有关问题

opencv 程序报错大家帮我看看哪的问题
#include"highgui.h"
#include"cv.h"



IplImage* dopyrdown(IplImage* in,int filter=IPL_GAUSSIAN_5x5)
{
assert(in->width%2==0&&in->height%2==0);
IplImage* out=cvCreateImage(cvSize(in->width/2,in->height/2),in->depth,in->nChannels);
cvPyrDown(in,out);
return(out);
}
int mian(int argc,char** argv)
{
IplImage* img=cvLoadImage(argv[1]);
IplImage* imgout=dopyrdown(img);
cvNamedWindow("zc",CV_WINDOW_AUTOSIZE);
cvShowImage("zc",imgout);
cvWaitKey(0);
cvReleaseImage(&imgout);
cvDestroyWindow("zc");
}

说main函数无返回值，但为什么其他的可以通过比如下边
#include"cv.h"
#include"highgui.h"
int main (int argc,char** argv)

{
IplImage* image=cvLoadImage(argv[1]);
cvNamedWindow("zc-in");
cvNamedWindow("zc-out");
cvShowImage("zc-in",image);
IplImage* out=cvCreateImage(cvGetSize(image),IPL_DEPTH_8U,3);
cvSmooth(image,out,CV_GAUSSIAN,3,3);
cvShowImage("zc-out",out);
cvReleaseImage(&out);
cvWaitKey(0);
cvDestroyWindow("zc-in");
cvDestroyWindow("zc-out");}


------解决思路----------------------
建议楼主先编译链接调试OpenCV自带的例子代码。
------解决思路----------------------

int mian(int argc,char** argv)

{

//你确定这是main 要细心