The hexadecimal code of 9241 is incorrect

MelancholyMing · October 15, 2026, 12:41pm

The hexadecimal representation of 9241 is 0x2419.

int m_morales{9241};              // base 10: 0-9
int a_apaec{0x24CD};              // base 16: 0-9 and A-F
int m_gargan{0b10010000011001};   // base  2: 0-1
int b_reilly{022031};             // base  8: 0-7
                                  // Leading with a 0 not the letter o.

github.com

MelancholyMing/cpp/blob/e6e47e11fb47e561d0eca71c6197163695b44caf/concepts/numbers/about.md?plain

# About
The built-in number types in C++ can be divided into integers and floating points.
Integers are whole numbers like `0`, `691`, or `-2`.
Floating point numbers are numbers with a decimal point like `6.02214076`, `0.1`, or `-1.616`.

## Integers
The following example shows the declaration and initialization of four different variables

```cpp
int m_morales{9241};              // base 10: 0-9
int a_apaec{0x24CD};              // base 16: 0-9 and A-F
int m_gargan{0b10010000011001};   // base  2: 0-1
int b_reilly{022031};             // base  8: 0-7
                                  // Leading with a 0 not the letter o.
```

When you assign a value to an `int` variable, you can do so directly with a literal.
A literal is a hard-coded number like `9241`.
There are different integer literals for several bases of the representation.
Decimal integer literals are the most common and use the digits `0` to `9`.

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siebenschlaefer · October 15, 2026, 1:44pm

You’re correct, 0x24CD is the only numeric literal in that section that does not have the value 9241.

But correcting it to 0x2419 would not show how a hexadecimal literal can contain digits in the range A .. F.
I’d rather have a value where the hexadecimal representation contains at least one digit in the range 0 .. 9 and at least one digit in the range A .. F.

Also, @vaeng often put pop-culture references into his texts. Here, the names of the variables evoke incarnations of a rather famous friendly neighborhood superhero across the ararchnid multiverse. I don’t know whether 9241 has a specific meaning in that context. If so, we should pick a suitable replacement.

ahans · October 16, 2026, 11:13am

It’s most probably just due to a typo when doing the conversion to hex: 0x24CD is 9421, so it’s like the other numbers with 4 and 2 swapped.

I agree that including a letter for the hexadecimal version is actually nice. How about instead of changing all numbers we leave 0x24CD as is and make the other three matching?

int m_morales{9421};              // base 10: 0-9
int a_apaec{0x24CD};              // base 16: 0-9 and A-F
int m_gargan{0b10010011001101};   // base  2: 0-1
int b_reilly{022031};             // base  8: 0-7
                                  // Leading with a 0 not the letter o.

siebenschlaefer · October 16, 2026, 1:51pm

I like that (and we should change the number in the following paragraph, too.)

@MelancholyMing Do you want to create a Pull Request?
You would have to make the change in three files:

concepts/numbers/introduction.md
concepts/numbers/about.md
exercises/concept/freelancer-rates/.docs/introduction.md

If not, @ahans (?) or I will do that.

ahans · October 16, 2026, 2:06pm

There is already a PR, I re-opened it now. Let’s give @MelancholyMing a chance to react here or over on GitHub.

siebenschlaefer · October 16, 2026, 2:09pm

Oh, I missed that. Great!