please help me to find the error - c++

Question

following code is for Detecting lines with Hough transform.But this code doesn't work properly.It says "cannot open pic1.png".Can you please check this code and tell me what is wrong with this code.Please help me. I am using openCV 2.3 library and visual studio 2010.Thank you.
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include"cv.h"
#include"cxcore.h"
#include"stdafx.h"
#include <iostream>
using namespace cv;
using namespace std;
void help()
{
cout << "\nThis program demonstrates line finding with the Hough transform.\n"
"Usage:\n"
"./houghlines <image_name>, Default is pic1.png\n" << endl;
}
int main(int argc, char** argv)
{
const char* filename = argc >= 2 ? argv[1] : "pic1.png";
Mat src = imread(filename, 0);
if(src.empty())
{
help();
cout << "can not open " << filename << endl;
return -1;
}
Mat dst, cdst;
Canny(src, dst, 50, 200, 3);
cvtColor(dst, cdst, CV_GRAY2BGR);
#if 0
vector<Vec2f> lines;
HoughLines(dst, lines, 1, CV_PI/180, 100, 0, 0 );
for( size_t i = 0; i < lines.size(); i++ )
{
float rho = lines[i][0], theta = lines[i][1];
Point pt1, pt2;
double a = cos(theta), b = sin(theta);
double x0 = a*rho, y0 = b*rho;
pt1.x = cvRound(x0 + 1000*(-b));
pt1.y = cvRound(y0 + 1000*(a));
pt2.x = cvRound(x0 - 1000*(-b));
pt2.y = cvRound(y0 - 1000*(a));
line( cdst, pt1, pt2, Scalar(0,0,255), 3, CV_AA);
}
#else
vector<Vec4i> lines;
HoughLinesP(dst, lines, 1, CV_PI/180, 50, 50, 10 );
for( size_t i = 0; i < lines.size(); i++ )
{
Vec4i l = lines[i];
line( cdst, Point(l[0], l[1]), Point(l[2], l[3]), Scalar(0,0,255), 3, CV_AA);
}
#endif
imshow("source", src);
imshow("detected lines", cdst);
waitKey();
return 0;
}

Answer 1

It's looking for pic1.png in the same directory that the executable is running from.
You either need to copy the image to the same directory or enter the path (either full or relative) to the image file.

Answer 2

Mat src = imread("pic1.png", 0); // put the image pic1.png at the current directory.
Mat src = imread("C://...", 0); // at some other directory like #ChrisF stated.