I removed the note about Titanic.

My solution is better because it’s simpler, more concise, and easier to read. Using byte-level operations keeps it efficient and well-suited for ASCII strings.

(OP's language was Ruby) re-raised there as an issue

Fixed in this fork

Forked and approved

• Restructured tests

• Use approx equality

• Added useful assertion messages

• Removed unnecessary block of tests

Cool

In Python is very simple

Example

age = int(19)
txt = str("Hello my name is Beno, i'am {} years old")
print(txt.format(age))

Added const for the char* r

That's just a formatting preference. What's I think is a bad formatting preference is putting anything after a scope-closing } on the same line.

Just a minor Feedback:
if you're using the curlybrackets, then put them in the next row so the code is simpler to read.

petty mid

char fanis(char r, int k) {
for (; *r; *r++)
*r = k + *r;
return r;
}

+1
https://www.snopes.com/fact-check/titanic-first-sos/

Maybe change the function nameto follow best practise, like equal_sum?.