because after installing 2017, 2015 seems to have disappeared from the installed programs list.
it is not a huge deal because I only needed 2015 for a program that now requires 2017. but, I am wondering because I never had something like that happen before.
No, they can live side by side and installing one will not uninstall or replace another. Each particular version is required depending on how the programs you're using is actually compiled.
I would simply keep both installed so I can just forget about it. On 64 bits systems, I would also install both x86 and x64 versions of each one.
but, it replaced 2015, as it is no longer installed.
anyway, I found that 2017 is basically an updated 2015 and is backwards compatible.
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