Can a 'c' program runs on Linux 7.1 which is compiled on Linux 6.3 or Linux 6.6
 

Can a 'c' program runs on Red Hat Linux 7.1 which is compiled on Red Hat Linux 6.3 or Red Hat Linux 6.6?

Yes.
As long as you either ensure that it has no version dependencies, or is static compiled.
Many applications are written so, otherwise they would have to be recompiled for every library version change and the maintainers would go quickly insane.

Ok, perhaps a bad way to express it, but those of us who are insane did not get here THAT WAY! ;-)

I assume, based on the version numbers you've listed, that you're talking about RedHat Enterprise or CentOS? Please be specific about the systems you're describing, there is no such thing as "Linux 7.1" or 6.3 or 6.6.

Usually, yes.

What kind of c program? What all does it interact with?

there is no operating system called "linux 7.1" nor "linux 6.3 or 6.6"

now there IS a OLD!!! Debian 7.1
a current RHEL ( RedHat Enterprise Linux ) 7.1 and 6.7

if you are referring to RHEL 6.3 ( the out of date version --by 4 versions and over 2 years)

will that run on RHEL 7.1
WHO KNOWS ????

you have not informed us as to WHAT this unknown program is
it might run?
it might not run?
it might KILL your install ?
WHO KNOWS ?

Viskuma,

Welcome to LQ. Perhaps reviewing this link will assist you in making your questions more clear.

- RT