I think it was NULL itself. It was a long way until we realised we don't want invalid values and could use the type system to help us use special values safely.

It was definitely an interesting way to allocate pointers. I did once have a very large project where devs didnt understand this and resolved hundreds or more off by one and memory overwrites in C due to this feature.

But at the same time, I think blaming the software was kind of a cop out. Devs were in a hurry and simply didnt respect the rules. Given todays software engineer at large. Nerfing programming languages so they cant destroy things might not be a bad idea. But AI will nerf everything.

Zero terminated string is a special case of sentinel value termination.

And sentinel value terminations make a lot of sense when you have punch cards and fixed length records that you need to carve into pieces.

Nobody expected any decisions they were making in the 1960s and 1970s to have any bearing on computing a half-century later. They all expected to have their mistakes long papered over by smarter people at some point.

But we ALL make the mistake of underestimating inertia.

In addition to having to pick a size for the length counter and then, later, having to differentiate between lengths in bytes, codepoints, and glyphs, you can't subdivide a Pascal string using pointer arithmetic. To pass just the end of a string into a function, you have to either copy the tail of one Pascal-style string to another with a smaller size value, or your string has to be a struct with an integer and a pointer to the actual data instead of just an integer stuck on the beginning of the string. The first is a lot of copying in some cases, the second raises the specter of structs with invalid pointers. That's not to mention the potential problems that would cause with caches.

compared to Von Newman versus Harvard architecture for LLMs? I think that's a far bigger mistake.

> Pascal style strings were much safer.

The limitations were brutal. Initially you could only have 255 bytes in a string. The length of a string and the size of the allocation are now separate and you may need to think about that unused memory in your design. The problem now doubles with the introduction of UTF-8. Your string size is in bytes and you need to track characters separately.

If you want to create an array of strings you either need to specify the length of all strings and accept the memory overhead or have an array of pointers to strings. If you use an array of pointers you may end up choosing to use the 'nil' value as a sentinel that means "end of list." So we're right back where we started.

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Because someone decided to downvote this HN has limited the speed at which I can reply. This site is tragic and I'm fully done with it now. You can spread propaganda and poorly sourced zeitgeist and be among friends but if you try to have a genuine conversation about programming languages you are made to be unwelcome immediately. Screw this.

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> No other data structure works like this.

The linked list.

> You can't mess this up in an array

C happily decomposes arrays into pointers. You can erase your length information from the type. This was an intentional decision.

> Strings are the only data structure that assume there will be a NULL at end.

Which is why almost every string API has a version that allows you to specify the maximum length. The fact that you can use a NUL doesn't mean you have to. Which is why the concept of "sentinel values" is broadly used in many types of applications you haven't considered here.