1. Why do programmers always mix up Halloween and Christmas? Because Oct 31 = Dec 25.
The joke here is that Octal 31 (which abbreviated looks like October 31st, Halloween) is equal to Decimal 25 (which abbreviated looks like December 25th, Christmas).
Decimal and octal are two number systems with different bases.
Decimal is the base-10 number system that everyone is familiar with. A number system has as many digits as its base number. That means a base-10 number system 10 digits (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) and is where it gets its name from (decimal, from Latin decimus, means tenth).
When you get to a number that is higher than the highest digit, you add another column to the left, so you count like 8, 9, 10, 11, 12, and so on.
Octal (from the Latin root oct- meaning eight) is a base-8 number system commonly used in programming. A base-8 system means it has 8 digits (0, 1, 2, 3, 4, 5, 6, and 7). When you get to a number higher than 7, you also add another column, so you count like 6, 7, 10, 11, 12, and so on.
If we convert the octal 31 to decimal, we end up with 25. Watch: if we break octal 31 out to a math equation, it ends up being 3 x 81 + 1 x 80 = 3 x 8 + 1 x 1 = 24 + 1 = decimal 25.
To convert the other way, you start with the biggest power of the base (8, in this case) you can divide by and get a whole number, then take that and divide the remainder by the next smaller power until you get to the 0-th power. Then you just combine the digits together. In the case of 25, we need to start at 81: 25 / 81 = 3, remainder of 1 / 80 = 1, so 31.
“Why do programmers always mix up Halloween and Christmas? Because Oct 31 = Dec 25″
2. There are 10 types of people in this world. Those who understand binary and those who don’t.
This is a binary joke; binary being a base-2 system. Since it is a base-2 system, it has only 2 digits, 0 and 1.
If we convert binary 10 to decimal, we get: 1 * 21 + 0 * 20 = 1 * 2 + 0 = 2.
So, the joke means “There are two types of people. Those who understand binary and those who don’t.”
If you don’t understand binary though, you’d think there are ten types of people, which would be weird.
In addition to decimal (base-10), octal (base-8) and binary (base-2), hexadecimal (base-16) is also used commonly in programming. It uses the letters A, B, C, D, E, and F as the “digits” above 9.
“There are 10 types of people in this world. Those who understand binary and those who don’t.”
3. There are two ways to write error-free programs; only the third one works.
This joke refers to the fact that it is actually impossible to write an error-free program.
It is possible to write a program that seems to have no errors, usually referred to as “bugs” in programmer lingo, but Lubarsky’s Law of Cybernetic Entomology states “There is always one more bug.” The bug may be so tiny and under such specific conditions that you’ll never see it… but there is always one more bug.
Since there is always one more bug, the joke says only the third, non-existent method is the only way to write an error-free program.
“There are two ways to write error-free programs; only the third one works.”
4. The best thing about a Boolean is even if you are wrong, you are only off by a bit.
A Boolean is a data type which can only have one of two possible values: true and false.
A data type just means what type of data is held within something like a variable.
Variables in programming are similar to variables you might have seen in math class, with the difference being that a variable in programming can represent more than just a number. It could, for example, hold an alphabetic character like “c” or a whole word or phrase like “Hello World”, commonly called a string or a Boolean.
Booleans are typically stored within a bit, which is the smallest amount of storage in a computer. It holds a single binary digit. Binary, being a base-2 number system, means it can only hold the value 0 or 1. In the case a Boolean, 0 usually means false while 1 is usually used for true.
The joke then, is that if you have a Boolean, the most you can be off is a bit, which would just be 0 or 1.
“The best thing about a Boolean is even if you are wrong, you are only off by a bit.”
5. A good programmer is someone who always looks both ways before crossing a one-way street.
This joke refers to the fact that, as a programmer, you can’t make assumptions about how things will behave in your program and always have to check everything.
For example, if you ask a user to type in a number, a good programmer won’t just assume what the user entered is a number. They need to check that what they got is actually a number and not a word or symbol or was left blank. Then, they need to check to make sure that the number is within the range that they were expecting (for example, -3 wouldn’t be a valid value for “How many people are attending?”).
Thus, the joke refers to the fact that they programmer can’t just assume because the road is one-way that everyone is going to follow that rule.
“A good programmer is someone who always looks both ways before crossing a one-way street.”
Now you can chuckle along with your programmer friends. Stay tuned for Part II next week!
In the meantime, jump to all iD Tech Programming Courses for kids and teens.
Got another programmer joke or developer joke to share? Post it in the comments!