How do I compile a C program that contains a OPENCV header file?h

edit

Thank you for your reply.Could you tell you the step?
this is my command

emcc -O2 ss.bc -o project.js -s WASM=1 -O3 -s "EXTRA_EXPORTED_RUNTIME_METHODS=['ccall', 'cwrap']" -s EXPORTED_FUNCTIONS="['_int_sqrt']"

#include "opencv2/imgcodecs/imgcodecs.hpp"
#include <emscripten/emscripten.h>
using namespace cv;
extern "C" {
int int_sqrt(int x) {
  IplImage *src = cvLoadImage("./a.png", 1);
  IplImage *dst = cvCreateImage(CvSize(src->width, src->height), src->depth, src->nChannels);
    //cvSobel(src, dst, 0, 1, 7);
    cvSobel(src, dst, 0, 1, CV_SCHARR);
    cvShowImage("dst", dst);
  return 0;
}
}

error info:warning: unresolved symbol: cvCreateImage

Did you compile OpenCV with emcc? https://docs.opencv.org/3.4.0/d4/da1/... Besides loading with cvLoadImage will probably not work so easily with WebAssmebly. You need to take care of the filesystem virtualization https://kripken.github.io/emscripten-...