Flipping The Pairs

The program asks for a number and then prints out all the positive integer values from 1 up to the number. However, the order of the numbers is changed so that each pair or numbers is flipped. That is, 2 comes before 1, 4 before 3 and so forth. For example:

Please type in a number: 6
2
1
4
3
6
5

num = int(input("Please type in a number: "))
r = 2
t = 1
while True:
    if t >= num:
        break
    print(r)
    print(t)
    r += 2
    t += 2

The code works fine with even numbers but then struggles with odd numbers. For example with the input 5 the result should be:

Please type in a number: 5
2
1
4
3
5

But instead my output comes out as:

Please type in a number: 5
2
1
4
3

Any help would be appreciated.

Looking at your own example, when num is odd and t == num, for example when num is 5 and t becomes 5, then the loop simply exits without executing for the 3rd time. If the expected output is to output 5 instead of 6 (because there is nothing to "flip"), you can simply do print(num) if num is odd. However this is inconsistent with the num=6 case as the fifth output is different, so I would recommend you double-check this.

Maybe there will be several solutions, but a simple fix is here:

num = 5 # assigned for simple testing
r = 2
t = 1
while t <= num:
    if t != num:  # if t == num, skip the below line
        print(r)
    print(t)
    r += 2
    t += 2

An one-liner example:

print(sorted(range(1, num+1), key=lambda x: x + 2 * (x % 2))) 

With list comprehension:

def fn(x):
    return x + 2 * (x % 2) - 1
print([x if x==num and num%2 else fn(x) for x in range(1, num+1)])

More readable version of the above example:

output = [x + 2 * (x % 2) - 1 for x in range(1, num+1)]
if num % 2:
    output[-1] = num
print(output)

You can print(r) only when r <= num, and move the t > num check after it:

num = int(input("Please type in a number: "))
r = 2
t = 1
while True:
    if r <= num:
        print(r)
    if t > num:
        break
    print(t)
    r += 2
    t += 2

you can do a simple change to your exiting code like below

num = int(input("Please type in a number: "))
r = 2
t = 1
while True:
    if t >= num:
        if num % 2 != 0:
            print(r-1)  # Display the last odd number
        break
    print(r)
    print(t)
    r += 2
    t += 2

The output will come as desired