For Loop passing the index to filename

g_paschoal · 11-01-2013, 05:22 AM

I am working with Magick++ API on linux and I am reading multiple images, processing them in for loop and then I need to write them in the for loop as well passing the index value "i" to the filename. However I don't use sprintf, I use the method from Magick++ which is image.write();

How can do it ? See part of my code:

Code:

int main(int argc, char **argv) {

// ImageMagick Stuffs

	InitializeMagick(*argv);

	vector<Blob> myblob;
	vector<Image> imageList(7);
	imageList[0].read("/cars/placa1/2.png");
	imageList[1].read("/cars/placa1/4.png");
	imageList[2].read("/cars/placa1/9.png");
	imageList[3].read("/cars/placa1/9_.png");
	imageList[4].read("/cars/placa1/e.png");
	imageList[5].read("/cars/placa1/b.png");
	imageList[6].read("/cars/placa1/g.png");


	for (unsigned int i = 0;  i <= imageList.size() ; ++i) {
		imageList[i].resize("30x50");
//		imageList[i].write("/cars/results/%d.png");
		imageList[i].write(&myblob[i]);
	}

This code compiles but crash on runtime.

Code:

root@ubuntu32:~/workspace/ImageM/Debug# ./ImageM 
Segmentation fault (core dumped)

Any help will be appreciated. Thank you very much

andrewthomas · 11-01-2013, 05:32 AM

I don't use Magick++ but have you poked around over here:

http://www.imagemagick.org/discourse...wforum.php?f=1

It might also be helpful if you posted a bigger portion of the program, someone more knowledgable may be able to figure it out from what you posted, but I certainly need more of the code.

g_paschoal · 11-01-2013, 06:29 AM

Thanks for your help, I will post on that forum.

ntubski · 11-01-2013, 10:01 AM

Code:

    vector<Blob> myblob(7); // need to initialize myblob vector
...
        // <= would go up to 7, but you want only 0 to 6
	for (unsigned int i = 0;  i < imageList.size() ; ++i) {
		imageList[i].resize("30x50");
//		imageList[i].write("/cars/results/%d.png");
		imageList[i].write(&myblob[i]);
	}

g_paschoal · 11-01-2013, 10:12 AM

Hi ntubski, thanks for your help.

I did what you suggested. It did compile OK and run OK.

However it is not creating any files.

this line should create a image with the same name it was read or could be something else I just need to get these images created in a for loop;

imageList[i].write(&myblob[i]);

Thanks

ntubski · 11-01-2013, 10:30 AM

Quote:

Originally Posted by g_paschoal

this line should create a image with the same name it was read or could be something else I just need to get these images created in a for loop;

imageList[i].write(&myblob[i]);

I would guess that a "Blob" is just a block of memory, so that line probably writes the image into memory, not to a file.

The commented out line would probably create a file, but you'll want sprintf to expand the "%d".

g_paschoal · 11-01-2013, 10:51 AM

got it....

I don't want to abuse even more of your time. But... would you please show me an example of how to use sprintf in this case ?

You know... I am a beginner in c++ programmer

Thanks

ntubski · 11-01-2013, 10:59 AM

Untested:

Code:

char filename[100];
snprintf(filename, sizeof filename, "/cars/results/%d.png", i);
imageList[i].write(filename);

g_paschoal · 11-01-2013, 11:14 AM

It worked

Thanks Thanks Thanks