Wash, Rinse, Repeat

At this point, we should be able to write a computer program that can accomplish many simple tasks. We’ve seen programs that determine if a number is even or odd, who wins in a game of “Rock, Paper, Scissors,” and whether a given year should be a leap year or not.

However, there’s one simple task that all of our current programming skills cannot easily handle. Let’s take a look at a version of that task and see if we can figure out how to solve it:

Write a program that accepts a positive integer between 1 and 5 as input, and then prints all integers starting with 1 up to the given number.

On the surface, this seems to be a pretty easy problem. We can solve it using a few if statements, as shown in this diagram below:

Following this flowchart, we can see if that if our input is 3, it would first print 1 since x >= 1 is true, then 2, then 3 in a similar way. After that, the next check is x >= 4, which is false, so the program would stop printing. So, this program meets our given specification.

Now, let’s see if we can generalize this program a bit:

Write a program that accepts any positive integer as input, and then prints all integers starting with 1 up to the given number.

Could we write this program using our current techniques? Unfortunately, we’d quickly find that it is impossible to handle. We’d need to create at least one if statement for each possible integer, which would make our code infinitely long.

So, is there a better way to approach this problem?