Re: Oh d-ai-ry d-ai-ry me

On 5/31/25 2:01 AM, Richard Heathfield wrote:

This evening I accidentally bumped into a chatbot, and I wondered whether it was any good at C programming.
 I was impressed when it solved Goldbach's Conjecture (admittedly for small n) and 5-disc Hanoi, but then I thought back to a recent thread here (which I have no intent of resurrecting), so I asked it if it could have saved me a job if I'd only asked it a few hours ago.
 Judge for yourselves!
 I asked: "Write a program that is valid C90 but invalid C99."
 ChatGPT said:
 Certainly! To illustrate this, I'll write a C program that is valid in C90 but invalid in C99. The key difference between C90 and C99 revolves around variable declaration and initialization.
Key Issue:
      In C90, variables can only be declared at the beginning of a block (before any executable code).
      In C99, variables can be declared anywhere within a block, even between statements.
 C Program Example:
 This program is valid in C90 but invalid in C99 because the variable x is declared after executable code.
 #include <stdio.h>
 int main() {
     printf("Hello, world!\n");
      int x = 5;  // Declaration after executable code (invalid in C99)
      printf("x = %d\n", x);
     return 0;
}
 Why it’s Valid in C90:
      In C90, all variable declarations must appear at the beginning of a block (before any code). This program would be valid in C90 because x is declared after the printf statement, but only the declaration of x itself breaks the rule in C99.
 Why it’s Invalid in C99:
      In C99, variables can be declared anywhere within a block, even after executable statements (not just at the beginning of a block). This is why the above code would cause an error in C99, as the variable x is declared after a statement (printf).
 Compilation Example:
 If you compile this program with a C99 compiler (e.g., GCC), you'll get an error similar to this:
 error: variable 'x' declared after statement
 To summarize:
      C90 allows this style (declaration after code).
      C99 does not allow it, so the program becomes invalid.
 

This is the reason why I tell people who write code that AI/LLMs can't ever replace them like this.  AI tools can only be a tool that you use. To write code, you'd still need to know something by yourself at the end of the day.
--
Rakin