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inline a=b+c

Started by gsus Feb 21, 2005 at 7:54 AM 3 replies 950+ views

Original Post

Feb 21, 2005 at 7:54 AM

Hi, im implementing a template class for image processing. I've overloaded operator+ template Image& Image::operator+ (const Image& img2){ Image ret(xdim, ydim); int i = 0; for(i=0;i<(ydim*xdim);i++){ ret.data = data + img2.data; } return ret; } but when i want to avaluate a = b+c this overlaoded funtion first needs to create image to store the sum. How can i store the sums direktrly in 'a'. A workaround woult be use somting like a.sum(b,c). tnx gsus

Qw3r7yU10p!

Feb 21, 2005 at 8:33 AM

look up expression templates

MaulingMonkey

Feb 21, 2005 at 11:42 AM

DANGER, WILL ROBSIN!!!

Quote:
Original post by Anonymous Poster
By the way, your operator + is bugged - you are returning a reference to a local variable. The variable ret will be destroyed when it goes out of scope, meaning the reference you returned will not be valid.

*points up* what he said. You need to return by value, or smart pointer of some sort, or handle class, or the like.

gsus

Feb 21, 2005 at 1:14 PM

oh...yes tnx.. the reference still there cos i've tried to tell the compiler to work on the 'a'.
I think ill use the a.sum(b,c) syntax. its not so nice an flexible, and i dont have the time to try expression templates. i thourght theres an easy way...

tnx

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