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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c++
Subject: Re: thread about the pros and cons of lambdas, but more about cons
Date: Thu, 26 Sep 2024 10:01:11 -0700
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Ben Bacarisse <ben@bsb.me.uk> writes:

> Ben Bacarisse <ben@bsb.me.uk> writes:
>
>> ... You can,
>> instead, do this (untested):
>
> I should have tested!  Of course you have to change the capture (at
> least for core) from '=' to '&':
>
>>   #include <functional>
>>
>>   int floodfill4(
>>     unsigned char *grey,
>>     int width, int height,
>>     int x, int y,
>>     unsigned char target, unsigned char dest)
>>   {
>>     if (width < 1 || height < 1)
>>       return 0;
>>     if (x < 0 || x >= width || y < 0 || y >= height)
>>       return 0;
>>
>>     size_t w = width, h = height;
>>     if (grey[y*w+x] != target)
>>       return 0;
>>
>>     std::function<void(size_t, size_t)> core;
>>     core = [&] (size_t x, size_t y) {
>
> Corrected-----^

Why do you think [&] should be used instead of [=]?