while loop

Question

int num = 1;
while (num < 6) {
cout << "Number: " << num << endl;
num = num +1;
}

in this case o/p is:Number: 1
Number: 2
Number: 3
Number: 4
Number: 5
Number: 6

but instead of num=num+1
if i write num=num++
it is giving o/p as number:1
number:1
.
.
.
infinite times

why?

Answer 1

you should user num++
num = num + 1
or
++num
or
num++

Answer 2

That u have written is
num = num = num + 1

Answer 3

It will give you syntax error