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Mat img = imread(..) vs img = imread(..)

asked 2015-03-04 14:01:57 -0500

pingping__ gravatar image

i have img as a member in the .h file, but when i use

img = imread(..);

in the .cpp file, it crashes. however, using

Mat img = imread(..);

works. what is the difference? thanks!

note: opencv3.0 with qt

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"it crashes" IS NO ERROR MESSAGE! What exactly happens? Which message do you get?

FooBar gravatar imageFooBar ( 2015-03-05 04:18:17 -0500 )edit

Is your member in the header file declared public? Is it inside a namespace? The second declaration won't even use your global variable, but rather create a local img object withing the scope of your cpp file, but not update the value of your global img object.

However I am not sure if you can make a non static object in header files. Never done so before, only know the principle.

StevenPuttemans gravatar imageStevenPuttemans ( 2015-03-06 02:48:20 -0500 )edit

@FooBar there werent any error messages... a window popped up saying it stopped running and that it is checking for a solution, and on my Qt creator IDE, it says after the program closed, this: The program has unexpectedly finished.

@StevenPuttemans yes it was in the header file, but in private instead. I tried putting it as public, but it was still the same... I actually dont want to make it a local variable, but it seems like it wont crash if i do it that way.. could it be that it wasnt initialized to something? not sure how this works.. :(

pingping__ gravatar imagepingping__ ( 2015-03-08 21:42:27 -0500 )edit

@pingping__ it seems to me that you need to dig deeper in C++ basics of how header and source code files work together. This seems to be not an OpenCV problem at all.

StevenPuttemans gravatar imageStevenPuttemans ( 2015-03-09 04:49:13 -0500 )edit

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answered 2015-03-06 01:32:08 -0500

juanmamdp gravatar image

In the code that gives you an error, img is defined within the scope of that variable?

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Thats not what he wants. The reason of declaring public variables in header files is that you can use them over several cpp files...

StevenPuttemans gravatar imageStevenPuttemans ( 2015-03-06 02:49:01 -0500 )edit
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Asked: 2015-03-04 14:01:57 -0500

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Last updated: Mar 04 '15