Never seen before C++ for loop

Question

I was converting a C++ algorithm to C#. I came across this for loop:

for (u = b.size(), v = b.back(); u--; v = p[v]) 
b[u] = v;

It gives no

Answer 1

In C everything non-zero is true in "boolean" contexts, such as the loop end condition or a conditional statement. In C# you have to make that check explicit: u-- != 0.