Can't use strrev() function in c++14?

on my codeblocks it worked fine but on codechef’s online ide it said “compilation error”,
what do i do?

You can use this
string rev = string(str.rbegin(),str.rend());
check this

You can use reverse(s.begin(), s.end()); to make the change in s itself.
If you want it stored in a different variable you can use the method @poojitha_792 has mentioned above.